Most Youtube videos showing videogames have people talking over the gameplay. To show potential viewers that their videos aren't like that and were made with only the actual sounds from the game, English speakers add "no commentary" to video titles. What is the Japanese equivalent phrase in this context?
From what I've seen, it understandably varies, as there are many ways to express the same thing.
For instance, if there is no commentary whatsoever, you might see: 声無し or similarly 声なし (without voice, e.g. http://www.youtube.com/watch?v=-Kny-ik8Vr0), or perhaps more ambiguously 実況無し or similarly 実況なし (without 'reporting live', e.g. https://www.youtube.com/watch?v=_ddKRIVnzKw)
But, if there is no voice commentary, but some text-based commentary, you might see: 声無し字幕解説 or similarly 声なし字幕解説 (without voice, with text captions e.g. http://www.youtube.com/watch?v=f1GCwxOSTjs)
There may well be other iterations I've not put, so I would also wait back on other answers!