How to join video files. (.001, part01.rar, .r00, .__a, etc)

What the hell are you talking about?

There is no size limit for split files (unless you have a very old OS or filesystem).

And "PURE AVI" is not split by definition.
 
I just joined HF and have been downloading some avi's using hotfile. Many of these end in .avi.001 , .avi.002 or in the alternate .avi_a , .avi_b I am on a mac and have not yet found a program or a way to join these types. Seems weird these are the types of files available for download yet so hard to join them.

Anyone of any advice or programs for mac to join the above mentioned file types? Thanks.
 
although not related directly to joining, jdownloader will join and/or unpack rar files etc automatically upon the download(s) completing. can save a bit of time and hassle.
as far as general ease of usage goes, i use 7zip and HJSplit.