Youtube quality pixelated when in an area with a lot of visuals

[mark-v-h]

Hello everyone, I am a starting youtuber and I have a problem which I can't seem to fix. Everytime I record a video in 1080p60 and upload it to youtube (after rendering in vegas pro 15) it comes out in good quality when there is not a lot going on on the screen, but when I come in a area in a game with a lot of visual effects the whole quality goes downhill rapidly. I am really frustrated with this since I tried A LOT of things to fix it. So here is an example of one of my videos: https://www.youtube.com/watch?v=6_r7-KeDYNQ

In the beginning the quality is alright from my facecam and from the game but if you skip to 28:30 the quality of the facecam and the game is utterly pixelated and I have no idea why. These are my render settings in vegas pro if anyone is interested: MAGIX AVC/AAC MP4 >>> Internet 1080P60fps >>> custom template:http://prntscr.com/loj8oa

I record with nvidia shadowplay: http://prntscr.com/loj8yu

If anyone knows a fix then you'll be my hero haha.
Thanks!

 

[mark-v-h]

EDIT: When uploading a video on youtube it also says: 'Your videos will process faster if you encode into a streamable file format. For more information, visit our Help Centre.' even though it is rendered.