I dont know of a universally working method - the
http://user:pass@url.com isnt supported in most places as it is insecure...
Some hosts have variations of scripts allowing it, like
https://support.cloudinary.com/hc/en...cted-resources - but if that works with the upload scripts of the individual tubes is a different thing - i doubt it.
I think putting them in an unprotected place is the most likely solution:
A) No, doesnt have to take much space. The tube doesn't feed from the location generally (the hun does for instance, but there they're temporary) - so you can clean them out before they eat too much space
B) You can actually copy/paste on ftp (depending on the client, sometimes it needs enabling in the settings) - but the easier way would probably be to simply start an upload to both the members and the unprotected directory simultaneously whenever wanting new stuff up there