Adding cover art to mp4 files

I have extracted a frame from each MP4 file I have using FFMPEG, and the file name is the same as the mp4 file.. except as a jpg... so Video1.mp4 & Video1.jpg
Is there anyway to add each .jpg as the cover art for the corresponding mp4 file but doing all of my files at once?
I know I can drag the cover art file one at a time, but this will take me forever. I was hoping there was another way using mp3 tag or an add on or something?
I read something about an addon Called Coverartdisc but the site seems to be malware infested now so i cant download it.
Any help would be greatly appreciated.

Create an action of the type "Import cover from file" (either as Action group or as quick action)
Format string: %_filename%.jpg
or if there are no other picture files in the folder:
Format string: *.jpg

Thank you for that ohrenkino, thats great and working.
Cheers