Just re-read your first post again. Didn't realise you could do 'open in' with Filebrowser.
Just tried it now and played the video in GoodPlayer. It worked fine, but it isnt really the solution I'm looking for.
The problem is that FileBrowser needs to download the file locally before transferring to the video rendering application. This process can be time consuming.
For example, i tried a relatively small 173mb AVI file. This took 1min 30secs at a rate of 1.5mb/s to download to the Ipad using filebrowser. Imagine trying to do the same thing with a 3gb MKV for example. That would take about 30mins.
It's not like my network is slow as I'm on 802.11n 5ghz, so i think this speed limitation is related to either the ipad hardware or filebrowser itself. (copying data from NAS to MBP is a lot faster)
What I was hoping for was an app that would allow me to stream videos wirelessly from my NAS, thus negating the need to download/copy over the file first. By the looks of it though, I don't actually think this app exists