As seen here:
There don’t seem to be any unusual steps needed to produce this bug, just posting a youtube video will do it. Affects videos posted before today as well (assuming a recent update is the cause).
Everything else related to the video (actual link to original, video replay) is unaffected.
Update - this appears to only applies to the image generated before the actual video loads. Clicking ‘play’ and loading the video switches out the /devicesupport URL for the title of the Youtube video.