Back to your two screenshots. Both of them were played at 1080p60 (FullHD at 60 fps), right?
Both of them are re-encoded at YT via VP9 codec. Don't leave the other videos at "auto" speed, as your second screenshot mentions. Stick all to 1080p60 while benchmarking them.
If there is a substantial difference of that two videos, then it's the portion/quota of movement within the video (content). Your first screenshot clearly shows a game play (continously fast movement, i suspect). The other screenshot shows more static content with low to no movement from frame to frame.
Please look if your buffering issue appears really on your own uploaded videos only. Compare them to other videos of same kind and nature (sport events with really lot of movement in the material over long period).
Again: Your download bandwidth is estimated with 3 mbps only. This is typically enough for static content, but may a clear bottleneck for demanding videos which require wider download bandwidth for large portions of seconds or even minutes continously. So videos with fast changing content may be affected by a (whatever the reason is) low download bandwidth on your internet connection.
Btw: Open a taskmanager while viewing such demanding content. What says your cpu and/or gpu utilization meanwhile, especially if buffering (running circles) happens?