Change breaks custom HD feeds

[kariudo]

d7d1ba5dae6b473789ea8f34b925033891b05fb9

The aforementioned commit broke all of my custom RSS feeds since they all used MKV for HD releases. I had to fork and revert this change to fix my build after it auto updated breaking my downloads.

I would like to request that the qualifiers (file extension and regex 720/1080 strings) have a configurable option in the preference pane to accommodate at least custom feeds if not all feeds.