For AV, Avast is a good free one.
You can get apps from the Goodereader app store, slideme, handago, aptoide but install your AV first...
Dolphin browser has a video add-in for watching shows.
An app that I really love (requires an inexpensive subscription) is DroidTV. It downloads your selection of TV shows to your tablet for offline viewing as soon as they become available. The selection of shows is quite extensive and you can choose as many as you want from several different networks all from the "tv guide menu" in the app. Works great on the Vox.