Can I post highlights of other people's replays?

[Y0lo]

You'll probably get away with it, assuming you have voice over too, just make sure to give proper credit.

Well, generally speaking I will ad non copyrighted music, and I do give the credits on the title.

 

[Marypop]

You need written permission without it that person can flag your video. Giving credit is NOT enough if you are using other people's copyrighted material. Why written, that person can change their mind and then can flag your video and you have no proof of the original release form.

 

[BeanTubes]

I would defiantly ask them for their permission just in case you monetize the video and get flagged