What are you using? Premiere? Just demux the mkv using something like tsmuxer. It’ll give you a .264 file that can be imported into premiere.
That’s what he means by res, yes. If you take an 8gb or 22 gb and convert it to a lossless format, of the same resolution and duration, it’ll end up being roughly the same size. Though lagarith is compressed (but lossless) so difference in artifacts and grain from the two sources might have minor effects.