Youtube is banned in some countries. It is slightly annoying, but I am sure there is a way around it. Perhaps someone such as a moderator could re-upload on behalf of Wobblyyy.
Bandicam files or just files in general could be inflicted with viruses as such. This in turn could get the original poster in a lot of trouble. Furthermore, it is a better idea to have the evidence kept on youtube, in my personal opinion, for the sake of record keeping. That way the user's evidence is kept as a permanent record against their actions it is easier to get multiple opinions on the evidence at short notice and if the user was banned unfairly there may be a way of them reviewing the evidence without risking them downloading it and altering it to make themselves look innocent. :)
Just my opinion on it though.