If you go to !videos@lemmy.world and scroll you’ll see some of the posts have a youtube thumbnail image, but not all.

I wanna post YouTube videos, but no one seems to engage much without a thumbnail, which makes sense, but I’m not sure what would result in the post actually having a thumbnail

If anyone has advice or guidance I’d appreciate it :) Thanks!

EDIT: so far it seems like it’s potentially a combination of what version of lemmy the posters account is running, and how that instance is configured…

  • Sergio@slrpnk.netEnglish
    0·
    4 days ago

    It looks like your “edit” is right (version of lemmy and instance configuration are an issue), with the additional complication that sometimes where it is hosted makes a difference (sometimes the youtube summary is in a different language and/or won’t grab it because of regional restrictions) and sometimes the reader app/web interface grabs their own thumbnails and/or may not display thumbnails and/or may even try to just embed the video. There was a post on techsupport a while back about this: https://lemmy.world/post/20180043

    I post to !fullmoviesonyoutube@lemm.ee from slrpnk.net and to get a thumbnail, I do the following:

    • get a thumbnail image file. either grab it from wikipedia, imdb, or by a screencap that I trim. put that file somewhere on my computer.
    • use the web interface with default client. It has a “thumbnail URL” field (which I didn’t see back when I had a lemmy.world account - probably version differences) but I can’t just upload the image to that field, so I have to…
    • go to the post “body” input field and click on the “upload image” button to upload the thumbnail image file from my computer. This uploads the image to the server and adds a line of code to the body input field that looks something like this: ![](https://slrpnk.net/pictrs/image/a-long-UUID.png)
    • copy the part from “https” to “png” and put it in the “thumbnail URL” field
    • usually I then delete that code from the post “body” input field
    • edit: of course, I still have to add the youtube URL in the “URL” field…

    I think this adds thumbnails, but of course I can never be sure because someone can always use a client or configuration I’m unaware of. That’s the price of freedom from a single corporate server and a limited choice of viewer clients.
    Ideally this whole process would be easier or automatic. I imagine the situation/process will change as time gones on.

    • treadful@lemmy.zipEnglish
      0·
      4 days ago

      Or shift+right click on the unplayed video and copy image link to get the thumbnail.

      I’ve been doing it manually because otherwise nobody watches it.

  • hono4kami@slrpnk.netEnglish
    0·
    4 days ago

    So I take a peek at the Lemmy’s source code.

    When you see a thumbnail and title of a URL (including YouTube video links) on Lemmy, what happens is that Lemmy server fetched the website HTML file and get the og:title and og:image (this convention is called OpenGraph protocol [1]) located inside <head> HTML tag.

    For example, for this video https://www.youtube.com/watch?v=MbYuEEU5e50, the OpenGraph metadata inside the HTML looks like this:

    <meta property="og:title" content="Flume - Lose It feat. Vic Mensa">
<meta property="og:image" content="https://i.ytimg.com/vi/MbYuEEU5e50/maxresdefault.jpg">

    Try opening the “Create Post” page, then enter URL of a YouTube video. You might notice that a loading spinner will appear. During this, the frontend of Lemmy is actually creating a request to /api/v3/post/site_metadata?url=[insert your URL]. When the backend side of Lemmy receives the request from front end, it will run this code [2] to fetch the HTML and parse it to find the OpenGraph metadata. If the metadata is found, the backend will return it to front end, and you willl see recommended title and the “Thumbnail URL” field should be filled.

    In theory, this should work fine, regardless of any website. I personally tried to view the HTML code of a YouTube video and the HTML file indeed contains OpenGraph metadata.

    But it doesn’t for YouTube videos in Lemmy somehow. And I’m not sure.

    I’m suspecting YouTube thought that Lemmy servers are bots and because of that instead of receiving the HTML file of a YouTube video, instead it received a HTML file of a captcha page. I think I’m gonna try contacting admins of my instance to see whether YouTube URL works or not.

    1. https://ogp.me/ ↩︎

    2. https://github.com/LemmyNet/lemmy/blob/a2a5cb091a2892793179760275cb56529891bcb6/crates/api_common/src/request.rs#L203 ↩︎

    • hono4kami@slrpnk.netEnglish
      0·
      4 days ago

      Also, this is a good tip in general:

      You can’t fetch title and thumbnail for YouTube links that starts with youtu.be. This applies not only in Lemmy, but other websites too, for example Twitter (even before Elon’s era).

      This is, IMO due to the link doesn’t really contain HTML and OpenGraph metadata. It only redirects you. If you try cURL-ing the youtu.be link, you will see that it doesn’t have a response body, only some header including Location header that will tell you where to redirect. The response code itself is 301.

      • Cris@lemmy.worldOPEnglish
        0·
        4 days ago

        There are people on shitjustworks posting youtu.be links on !videos@lemmy.world that do have thumbnails, so whatever they’re doing doesn’t seem to have that problem

        My .ee account has a field to put in a thumbnail URL, so other comments in this thread are kinda leading me to believe it may be a combination of instance version, and how the instance is configured

    • Cris@lemmy.worldOPEnglish
      0·
      4 days ago

      Most of them have it for me, but I just posted a video to the Souls-like comm and it doesn’t have one, which is really what I’m trying to fix :/

  • hono4kami@slrpnk.netEnglish
    0·
    4 days ago

    It’s because Lemmy can’t fetch YouTube thumbnails. I swear it used to fetch thumbnail and title automatically before, hmm

    • flamingos-cant@feddit.ukEnglish
      0·
      4 days ago

      It’s because YouTube puts a bunch of JavaScript at the start of the file (1MiB) before the opengraph tags and Lemmy only fetches the first 512 KiB (a fix was merged a couple days ago).

      • hono4kami@slrpnk.netEnglish
        0·
        4 days ago

        If you don’t put a whopping 1MB of JavaScript in your website, you’re doing web development wrong.

        /s

        • Enoril@jlai.luEnglish
          0·
          4 days ago

          Don’t forget to add also the 2856 partners intrusive code lines and cookies to have a “better experience”

    • TehBamski@lemmy.worldEnglish
      0·
      4 days ago

      I can testify to this. I was there. I was there when Lemmy so valiantly fetched ye old YouTube thumbnails.

  • Andrew@piefed.socialEnglish
    0·
    4 days ago

    It depends on what youtube is willing to provide. It seems more likely to provide a thumbnail if you use a youtu.be link than a youtube.com link.

    Instances running Lemmy from 0.19.4 onwards (I think) provide the option of providing a separate thumbnail manually, which is useful, but your instance is on 0.19.3.

    • Cris@lemmy.worldOPEnglish
      0·
      4 days ago

      Okay so it seems like the only people getting thumbnails on !videos@lemmy.world are from shitjustworks.

      No dice on using my .ee account though, that didn’t seem to result in a thumbnail either. But in the app I’m using, when on my .ee account there’s a field to put in a thumbnail URL which is interesting

    • Cris@lemmy.worldOPEnglish
      0·
      4 days ago

      I tried again with a youtu.be link and unfortunately no dice, so it seems it might be an instance issue, I’m gonna go take a look at the videos comm and see if there’s anyone on .world who posted and got a thumbnail. I might also try again from my .ee account