Mushoku Tensei Isekai Ittara Honki Dasu Ep.1-2 [Fansub][1080p][h265]

Quality isn't that good, bitrate looks very low.

I guess that's because the player doesn't support, (ultimately), h265 (HEVC) codec. Encoding it to h264 (AVC) might work:

ffmpeg -i "file.mp4"  -strict 2 -vcodec libx264 -pix_fmt yuv420p -preset slow -acodec aac output.mp4

For low-end machines (computer) with very low RAM, replace slow with ultrafast.
Note: this would take many hours.

What kind of retarded advice is that?

@kuddlesworth this a pre-release version, the anime comes out on the 10th of January

@harieamjari doing that is a waste of time, download the h264 version if your device doesn't support h265