Dropbox and Add Item Problems, Please help!

Hello! I seem to be having quite a bit of trouble, and a big part of that seems to be an issue with Dropbox, but to be honest, I'm not 100% sure... To put it simply, I can not add any items, and I swear, I've tried to figure out what might be wrong from reading the forum/doing research, but I just can't figure it out... I'm terribly inexperienced with this sort of thing I'm afraid... Eager though! Would so so SO appreciate any suggestions anyone out there might have!

Ok so, I'm working on this site here:
And am currently running the very latest version of Omeka, version 2.1.4, and my hosting is from Dreamhost. I guess I should also say, (If it is at all helpful...) That I am working on a Macbook Pro, and and that my FTP tool-thing is Fetch... Also I am running the Thanks Roy theme.

I can NOT add items, with or without dropbox. I need to add thousands of videos to this site, and am very much needing to use Dropbox, but so far I'm not having any luck at all... Dropbox installs without error, I can see the files listed inside of it, but when I try to batch upload, or even just upload a single file, I get a 404 error. One such error reads:

"404 Page Not Found

/files/original/a5f7e68595d9be6859be6c3b20b9abd17ec0ae.mp4 is not a valid URL"

Two things to point out with the above, I do have a 'files' folder in the Dropbox plugin folder, but I do not have anything called 'original', where is that coming from? Also, that long string of numbers and letters was not the name of the file I was trying to upload at all - does Omeka just assign files a new name like that, or is that evidence of something to be concerned about...?

or, another example that happens quite often:

"404 Page Not Found

/admin/dropbox/index/add is not a valid URL"

Also I guess I should say that when I have attempted to batch upload, it only seems to ever even attempts to upload 1 single file? And that item just seems to show up on the front page as '[Untitled]' every time...

I'm terrible at diagnosing these kind of problems - one thing I have thought of though relates to this line regarding the instillation of Dropbox:

"Make 'files' folder located in the /Dropbox plugin directory writable to the Apache server. For most servers, you can use the follow command to make the file writable: chmod -r 775 files."

It is true, I don't know if I'm doing this step right... In Fetch, I can go 'Get Info' for any item/folder, and there it gives me the option to make either 'group' or 'other' writable, and that does change the value next to 'UNIX equivalent'to 777 at most, but nowhere does it say anything at all about 'chmod'... Am I looking in the wrong place? Also, should just the 'files' folder be set to this, or all files in the folder as well...?

Please, if anyone at all can help, I would so appreciate it, I'm a bit at my wits end! Happy to provide and other bits of information needed of course to solve this problem. Thank you to all in advance!

All the best,