I e-mailed the guys at ME about their downsizing function for 4K videos. And it seems as though buyers can use their conversion to tool for any size or format but the pricing remains the same (If I understand correctly).

This seems like it could hurt potential sales for people who may want HD or lower rez files but don't want to pay 4K rates for them. What do you do with files at ME? Submit both 4K and HD versions?

Yes, exactly. I upload both 4K and HD and merge the clips so they show up in the search results as one clip but the buyer can chose between the HD and 4K option.

Obviously you are able to price them differently.

Sounds a lot of manual work. I'm already having troubles uploading 4K videos, for some reason, it can't handle more than 10-12 uploads at one time.

Does anyone actually make any meaningful income at Motion Elements to make the effort of uploading worth it?1

Not me. Maybe one sale every 2-3 months. Going to drop them.