The FA seem to have manufactured a situation whereby the author of the video is effectively the person who decides what will or will not be reported, and if this person is remotely connected to either of the two teams then how can this be impartial.
As someone who films matches in the same way and uploads the highlights online, let me comment on this.
For any Blue Square league match it is in the rules that full length copies of the match tape (usually a DVD) have to be provided (within 48 hours) to both clubs and to the referee's assessor. It has been known for the referee's assessor not to bother with his copy when the game has passed off without incident. It is also quite usual to receive a phone call from the club secretary asking for clarification of any specific incident in order to decide whether or not to launch and appeal - which now has to be done pretty much immediately due to new rules enforced. Likewise the away club can use the footage supplied by the home club to appeal too.
The match between Mansfield and Alty is an anomaly because, as far as I am aware, it is not in the rules of this stage of the competition that you must provide the away club with a copy of the game. Usually it is good manners to do so however. Likewise in the FA Trophy - in fact when York played Torquay United in the semi-final, Torquay refused to submit a video copy of the 1st leg to York so that York could use it in training for the 2nd leg. So you could say that while it might be seen as poor form by Mansfield they have not broken any rules.
The fact that the footage is on YouTube is irrelevant if it is from the Official tape, as it will be the official tape used by the FA to make any judgements regarding suspensions and other punishments.