jAlbum does not have a way of extracting a still image from an externally-hosted video to use to create a thumbnail for it. You can use a video editing program to extract a single frame, take a screenshot, or choose any other still image to represent the video in the album. This should be a full-sized JPG image, rather than a thumbnail.
Add the image file that represents the video to the album project.
Because the video must be connected to a single image, you cannot use album-level settings. You must choose the settings for this video under Image-Specific Settings. jAlbum cannot determine the dimensions or the length of an externally-hosted video, so these values should be entered manually. Enter the absolute URL for the video.
For a YouTube video, view the video on the YouTube site, and click the Share, then Embed links. If there is no Embed option, that means that the person who posted the video does not allow it to be embedded on any other site, and you will not be able to use it in your album. Make note of the width and height of the video, then copy the URL that's shown in the embedding code (use CTRL-C to copy it, then use CTRL-V to paste it into the Gromit settings, to avoid errors). The skin will accept any of the following URL formats:
For a Vimeo video, view the video on the Vimeo site, and click the Share icon, then click the Embed link. Make note of the width and height of the video, then copy the URL that's shown in the Link box (use CTRL-C to copy it, then use CTRL-V to paste it into the Gromit settings, to avoid errors). Do not include any autoplay parameters - the skin will take care of this automatically. The skin will accept either of the following URL formats: