I personally don't do youtube, but when I watch videos I prefer to see just highlights. If you do a commentary with like tips & tricks or discussions about the game, just give clips where you play good & where what you say is actually visible if possible (like for tips & tricks, or when talking about a specific map). If you're doing a commentary about the gameplay, I'd prefer just funny moments or good plays, but if it's too hard to find a lot of content, try just cutting out the parts where you're silent & nothing is happening. This means you don't always have to comentate, it won't be as awkward for both you & the viewers that way.