for large videos over 350mb here is what i do using ffmpeg to try and make it fit first without lowering bitrate. then the aspect ratio/dimensions. ffmpeg is in this context used as command/program in linux and it has a way to run on windows natively aswell.

 

ffmpeg -i input.mp4 -y -metadata title="" -b:a 60k -map 0:0 -map 0:1 -vs -sws_flags lanczos -pix_fmt yuv420p -c:v libvpx-vp9 -strict -2  -refs 2 -crf 25 output.webm