This happens when you submit a link to a spam site. When it happens to innocent people it's usually because some site has been mistakenly classified as a spam site, e.g. by an admin fat-fingering something on an iPhone.
I investigated further and that is in fact what happened. Youtube.com mistakenly got marked as a spam site. I unmarked it, so you can submit your video now. Sorry about that.
The other problem I've encountered on mobile devices (and even occasionally on a PC with a mouse) is that the voting arrows are small and quite close together, making it rather easy to hit the wrong one.
One possible solution would be to have only the arrow you click disappear, so you could always hit the other one and at least cancel out your own vote if you made a mistake.
You think? On my iPhone, the page width is about twice as wide as would be comfortable to read, so either you read tiny print or zoom and scroll constantly.
I hate doing this. I just want to see the comments for an interesting article and end up flagging it. I always hammer on the back button, but doubt it does any good.
I don't know if a single user flagging a post on accident has any real effect, but it makes me feel terrible.
An alternative to a mobile skin might be to have the option to "unflag" something. Even with a mobile skin, I could see submissions still being accidentally flagged.
