Ok, so your external drives mount, in the Debian branch anyway, in the /media file. I have 640Gb in an external enclosure that has 4 OS' and 2 large storage partitions.
The 3 HDDs mount in /media. The partitions mount normally in user space. All your flies go back to / if you think about it.
I have the external up right now and the path is /media/Holding-E/Debian for the file I am currently in.
Cinelerra is absolutely new to me. Just installed it about 2 weeks ago. However I do store my videos on a partition not in my OS although it is on the same drive. To make it easier to get into (not having to manually mount it each time I reboot), that partition is in in my fstab file and mounts that partition to /media.
Having just pulled up cinelerra I look for my video files. The path that Cinelerra is showing is /media/I-Holding/Holding/Catch-All/Video/Yup. Has the buggers all listed right there.
I do not know how long you have been playing with Linux but I can understand the frustrations. This is a link that I just fell on when I was feeling about the same. Have seen it linked a number of times since then. It is a good thing to read.
http://linux.oneandoneis2.org/LNW.htm
I never felt that the MS system made any sense at all in the ten years I ran it. I am one of the few people that I know that regularly put off problems by directly replacing system files from my install disk to my installed OS so I got pretty familiar with it. Linux with its owner ship permissions and file structure (pretty much Unix) is quite a relief to me. You do need to understand the system. I may one of these days.
If you are having better luck with the Kdenlive package I would use it. While I do not like the KDE desktop at all (just grinds me the wrong way) a number of KDE packages are pretty nice to have around.
K3b is a standard install on all my installations, for instance. Every once in a while I will run into something that Brasero will not handle. I have Xfburn and K3b. All three use different backends so if one doesn't do the job one of the others will.
Cinelerra is the only vid editor I have on here. I have no idea how to even use the bugger. When I do I will be trying others. Why did I pick it first? The list I read was in alphabetical order.
This is something I know nothing about. I hope you do. You may come across questions about this editing business sometime next month (not a chance of time before that).
If you have an answer for me on this use small words for a total noob.