Transferring avi from one app to another? How? Idownload+ will not play.

[therealriley]

Hi guys can anyone help? My brother uploaded a homevideo of my nieces birthday in an avi file and said I can download it into mymedia app on iPad. He has now removed the link so I can't get it again but I used an app called idownloads+ to download it and it does not play, it does have an option to open with and mymedia app does not show up, but a bunch of other apps do so when I select one it does nothing I tried it about 20 times now it says my iPad memory is full but it does not open in any other app? Even if I already open the app it suggest. It appears to be copying the file somewhere taking up the memory but does not show anywhere other than the original file in idownloads+
It's a big file around 500mb and I don't use a pc or have wifi just 3G so how can I move the file to one of my many other players to get it to work? I can't get the video again now as it used up most of my data limit and I only have a little bit to last me for a few days. Also my brother is away on holiday now so can't ask him how he does it.

Any suggestions please?