After trying out more apps including oplayer hd and I believe I tried most other video and media player apps on my iPad 1 ( not JB). For me, the best app remains Azul Media player. Everything I trow at it, plays perfectly. Also to be able to download from within the app and save is awsome. And if I find an exeption on a certain format that doesn't play in Azul, I use Xilisoft iPad magic for a fast conversion. Azul is stll the only one that has all the features I need and more.
Support is also incredible as the developer answers within a couple of hours and works on your ideas and tips. For 99 cents it's a giveaway and I strongly recommend it.