Proper is a term from the scene and it means that someone released a better/working version of it. It can mean that the previous release had for example an invalid serial number or a crack that wasn't working or it means an error was made in the process of encoding music, movies or tv.
Size is no good indicator on its own but it's an important part in the calculation. What's basically important is the bandwidth available for the video and with fixed size limits, the scene releases have to take some hits here. Some animated movies can produce amazing results with relatively small sizes of 2-3GB in 720p so there are always exceptions. My personal "rule" is that 720p content below 4000kbps is not enough to satisfy me and I've seen plenty of CTU/NBS tv-rips to confirm that.
It's not that easy, unfortunately. There aren't really any hardware players to support mkv files on a dvd, so you will need to find other methods of watching this stuff on your tv. When you burned the hd movie on a dvd, you most likely did a downconvert to the respective pal/ntsc resolution and reencoded the movie in the proper mpeg stream. That's a sure way of wasting quality.
There are quite a few ways out there to properly watch highdef content on your hdtv and none of that include burning on any medium (yet) and using a hardware solution for playback. Okay, that's not quite true, because there are ways to do this, take the xbox or playstation 3 for example, generally streaming is the best way to go for the moment. Other hardware players capable of mkv-hd-content are slowly starting out (see the
Popcornhour Networked Media Tank for an example) but they are not perfect yet.
edit: about SEPTiC .. they have a horrible reputation among hd enthusiasts and if you compare some screens between theirs and non-scene rips you'll
see the difference. Any hd movie will be better to watch than the dvd-rip in comparison but why settle for a 'cheap scene rip' if there are better alternatives out there? I don't see any reason to bitch about scene groups because they also deserve their respect for what they do - but truly, the only reason to download a scene-hd-rip is to watch it a couple of days earlier, before CtrlHD/ESiR or someone else does an encode. Because of my Usenet access I am downloading scene releases and they're fine to watch most of the time, whenever I want to 'archive' a movie though I try for a better alternative.