With Vloggers and Gamers a script can be hindering since you want to capture pure and honest reactions, this is true. But when some gamers and YouTubers see this advice they'll tend to just not edit their videos and upload a gameplay straight through - I wouldn't recommend this if you tend to be quiet a lot of the time while playing. There are several ways to solve this.
1. Edit the video with cuts so there is no silent/awkward parts
2. If you can't do cuts since you're trying to do a video where you show gameplay continuously, then practice practice practice with your commentating skills in speaking almost entirely throughout the entire video. Trust me, it gets boring when nothing is happening. This goes for Vloggers too, practice being around a camera because silence in a vlog is terrible. It is acceptable for short periods and there are exceptions but for the most part, no.
3. If you can't do either of the above, that's when writing a script comes in handy. But you are still trying to capture your essence and original reactions, so use a script almost as an outline so when you can't think of things to say, remember what you wrote down and then talk about that. It is VERY hard for most people to think of things on the spot and a script can help train your ability to improvise.