The explorer-crash when opening a folder that contain video files, is most likely coased by the explorer itselves not being able to show preview of video (icon). Probably a corrupt or not installed codec..
This is easily fixed by entering Folder property -> Show -> scroll down to “Always show icons, never miniatures”, and unmark this option!
Sorry if the terms is’nt correct, I’m not on an english windows.
This is also the reason why I never download or save a video to the Desktop.. (well, did it, crash computer totally, learned)
Hopefully this will solve issue no.1
Good luck