arghh. it took me a few reads of that sentence to understand. and i think i do now. here is a screen shot of how i've got my drive setup.
as you can see there's simply the time machine backups, then two folders just split into TV/Movies. are you saying, 1) it would be a good idea to select those two folders whilst still inside of the backup drive and make time machine back them up for additional safety?
or, 2) should i move them back to the Mac HD and do a backup on them from there?
i think i see what you mean, and having a full backup AND an accessible folder might be beneficial.
splitting the drive, arghh, i'm not sure how i'd tie that into the first suggestion mind.
this advice is greatly appreciated, i'm just not 100% certain yet which to do. which sounds better?

Yeah, that explanation was not one of my shining moments but I was in a rush so couldn't really clarify! Sorry about that!

I'll try again here.
OK, after seeing your screenshot it confirms how I thought you had it set up. So based on that, what I was trying to say is that with your
current setup, your "Movies" folder and your "TV Shows" are
never going to be backed up by Time Machine.
This is because Time Machine
automatically excludes the drive that its database is written to. It does not just exclude the "Backups.backupdb" folder that it creates on that drive, but rather the
entire contents of that drive- and there is nothing you can do in the Time Machine preference pane to change that behavior.
So now with that knowledge, you need to make a decision- do you want to backup the Movies and TV Shows folders and/or anything else you might choose to save to that drive?
If you
do want to backup that data, you have at least three choices of how to achieve that which I will list from worst to best:
1. Divide your external drive into two partions- one for Time Machine's backup folder (let's call it Partition A) and one for the Movies/TV Shows folders and other data (Partition B). This would allow Time Machine to backup to Partition A. That backup would include the contents of Partition B.
- I rate this the poorest solution because then your data
and the backup of that data exist on the same physical hard drive, so if the drive goes belly up you have lost both the original data and the backup of it.
2. Move your Movies/TV Shows data onto your internal drive and leave the external drive as one big partition as it is now for TM's exclusive use.
Better- but not best because although you now have all your data backed up to a separate drive, the data uses a lot of space on your internal drive.
3. Leave your existing external drive set up as now (1 big partition), but get another external drive for your Movies/TV Shows data and whatever else you might want to store there.
Best of the three because now your internal drive is still free of the large Movies/TV Shows folders and your data on the second external will be backed up to Time Machine's external. Now on the second external you could then exclude folders to your heart's content.
Now if you
don't want to backup that data, just leave things as they are now!
Hope it makes more sense this time around!