What I’ve been doing for my video/UE4 work so far is using the Coherent UI plugin.
I encode the video in a format suitable for a web player, write a simple bit of HTML to play it, and make it all available as a texture via Coherent UI. I have video playing in UE mapped to a surface and all via the material editor and Blueprints, I expect to need to add some C++ code for complex stuff I have planned but for basic use I’ve been fine so far.
At the moment it doesn’t support audio but I’ve been assured that should be coming soon and as my project doesn’t need it at the moment I’ve been fine.
I am also looking at the docs for the VP8/VP9 codecs with an eye to wrapping one of them in a UE4 plugin myself but that’s a much longer term project.