that feature Is really worthless (if you don't believe me try a benchmark) when you zip/rar video encoded with some codec you are compressing an already compressed file so you're no getting more compression, maybe a tiny percent , but not even a single megabyte.
It's funny how people have forgotten why large movies are in RAR pieces to begin with. The whole discussion about compression on RAR files is hilarious as it's based on made-up reasoning.
I think they will as it's one of the coolest features of XMBC to play video rar and zip files. Think of the hard drive space that could be saved!
Players play RAR and ZIP files not because of compression, but because they come as multi-part RAR/ZIP files from the source that initially uploads it. Large files come in multi-part RAR files for several reasons (depending on the scene, type of file, etc.)
1.-Because it's uploaded as it's being recorded, and parts are chopped off and uploaded as they're being streamed. This is automated and is how TV Series in HD are shared.
2.-Because it's shared in places that make it easier to do multi-part files (which minimize problems and errors and maximize multi-peer sharing with more basic protocols like FTP), where files can start being distributed before the whole file is complete.
Keep in mind, because it's important, that both RAR and ZIP are used in "STORE" compression mode, which means no attempt is made at compressing. RAR and ZIP (and actually more RAR than anything) is used not as a compressor, but as a packager (because, again, it supports multi-part on-the-fly chopping of a file, even as it's being written).
Now, players started supporting ZIP/RAR files started supporting it for a single, simple reason: Because people are lazy and didn't want to have to uncompress the files to end up with the same disk space used, for stuff maybe they'd see once or twice.
Then when HD files came up, people discovered a lucky effect of multi-part files: You can store multi-gigabyte files in FAT32 volumes (which can't hold anything above 4GB), which made it easy to use the most common disk filesystem in the world to move files around.
For these reasons, multi-part RAR carved a solid and profound niche in these set-ups, and won't go away soon.
But with it came ignorance by people who couldn't figure out why RAR was being used, and assumed it was due to compression. And on one side the proponents defend the format on merits it doesn't have and the haters complain about the format on arguments that have no bearing with reality.
I, personally, don't like RARs and always "uncompress" them. But I know where they come from and why they exist, and I'm OK with it.