I've only been able to upload genga and still images of layout for some reason because clips from anime when I try to upload say that I can't upload it because it has audio.
This is the method I use:
>>Screen record/download the clip
>>Delete the audio using a free video editor
>>Use https://www.onlineconverter.com/resize-video to change the aspect ratio and then upload. (this method works for genga but not anime clips)
What are the methods you guys are using or am I missing something here?

So screenrecording is never advised, it changes the frame rate of the animation. You need to cut directly from the source which involves downloading (or owning) the episode. From there, I recommend following this Avidemux guide written by Ajay (scroll down the page a bit): https://www.kanzenshuu.com/forum/viewtopic.php?t=32434&start=2000

the only thing I would add to the guide is: under "Configure" on the left hand side, the crf is set to 20 by default, lowering that to 15 or 16 instead will greatly improve the quality of the encode.

Additionally, make sure that you are always cutting from the most optimal source available, or at least close to. This means avoiding TV raws, sources which have been re-encoded to minimize file size at the cost of quality, anything which has been filtered to alter the colors, and many more pitfalls. If you ever have any questions or doubts feel free to direct message me, I'd be happy to help.