Wow, that's a $60 app (or $10 per year). I wonder how much of the code for that is actually open source.
It's a quality app and there's also a free version that might be enough for OP if his codecs are supported.
The free version I think will suit most people. It's what I use.
How?
Settings->Add files->via documents
That open the icloud browser (wierd name)
It works but it’s quite clunky. Either you have to copy over when you play directly the video it’s not in the library. Definitely not very intuitive or simple.