How can I get the Harlem Shake video to camera roll?

Me and my friends made a Harlem Shake video using the iPod touch app version and when we finished I clicked save to camera roll and it popped up saying "oops there's been a problem" so I clicked it a couple more times and the same thing happened so I then clicked share and sent the video to my mail. So the only question I have is, how do I save the video to camera roll from my gmail?