And as BT suggested, the FAQ should probably be updated to include this rule (unless the rule is no longer valid, in which case I'll discard this post).

I never knew of this.

I think a function to flag a thumbnail is a waste of time, in this scuba divers professional opinion.

I think that's a stupid rule. As long as the thumbnail is relevant, poignant or otherwise adds to the overall sift, like a title, tag or description, it should be up for customization, within limits (no pictures of turds on every post..).

I think it's a good rule. It's consistent with other related rules when submitting a video (title, tags and description should be reflective of the content). It would be fun to have creative license with thumbnails but I'm sure it would get abused. Not that anyone here would do such a thing, but I don't want to see a constant stream of "bewb" thumbs here

errr .. and yes, I'm a little concerned that I just said I don't want to see bewbs ..

I don't particularly care either way, but I do think that it's natural to assume that the thumbnail is a still from the video, and it's kind of weird when it isn't.

Why can't VS grab a random thumbnail shot from the video?

@Sarzy is exactly correct. The FAQ has been updated to reflect the requirement that all thumbnails *must* be take from a frame of the video content.

There need not be a flag to mark thumbnails inappropriate because if you go to the trouble of intentionally adding an invalid thumbnail to a video, your thumbnail editing privileges may just be revoked.