I'm not sure if i can think of any bands similar to what I've been looking for, but something along the lines of this:
http://www.youtube.com/watch?v=6Wzgsw9CwHg
bear in mind I'm not very familiar with post rock, but the few snippets i've heard of it are decent but would be more up my alley with a bit more aggressive, Gothenburg-y riffs and vocals.

Good thread, I used to be a huge Melodic Death junkie and I'm currently really into Post-rock, but I've never thought of combining the two. The closest I can think of is In Mourning's latest album, The Weight of Oceans. It's atmospheric, but not the most Post-rock thing in the world. They remind me of the link you posted, though.

Colossus - the first track off that album.
http://www.youtube.com/watch?v=YZ4ioEQ7okM

Nahemah is the closest I have in mind. Progressive Death instead of Gothenburg riffs, though.

http://www.youtube.com/watch?v=ijY9JIsGRww

Can you stomach metalcore at all? If so, try Of Virtue. http://www.youtube.com/watch?v=6me7qds4prQ

They're a metalcore band though they're more on the core side (very post hardcore sounding, a bit of hardcore, breakdowns, etc). Now I've only listened to their material once and I'm not very versed on it but from what I remember their full length has some post rock elements in it. I won't have my computer for another few days (and thus no music library) and I don't want to go hunting for the perfect song on youtube so try the one I linked. This band has a lot of very reverb-y sections and some acoustic sections as well. When the main part of the song ends at around 3:40, you can hear a very soft, distant type of sound that would fit no where better than a post rock song.

I've tried getting into In Mourning before and I always seem to lose interest halfway through their songs, but that track you posted was definitely the best song by them I've heard so far... I'll have to give the rest of the weight of Oceans a listen to now, sounds promising. Really liked that Of virtue track also, probly gonna have to hunt that album down now.

I would suggest mid to late

Swallow the Sun http://www.youtube.com/watch?v=drzAMT1kwEk

Can't wait to check out the recommendations posted so far. The track in the OP is pretty nice as well.
I think Ghost Brigade may be close to what you are looking for. They play a slow, marching style of melancholic sludge with some unbelievably catchy melodic riffs. Most people tag them as melodic death metal and associate them with Insomnium, but I think they fit neatly next to Callisto, Cult of Luna, and the like. Plus, the vocalist is remarkable.

Clawmaster (Great official video): http://www.youtube.com/watch?v=6kubmMxykI8
Breakwater: http://www.youtube.com/watch?v=u1MKBXGpsQ4
Lost in a Loop (One of my personal favorites): http://www.youtube.com/watch?v=rrutk9KaOnE

I'd further recommend starting with their latest album which has the "post" influences more pronounced.

Thirding Ghost Brigade. They even have a complete post-rock song 22:22 Nihil. Anyone else think latest Insomnium album had some post-rock influence?

It could be said to have some influences but I think they have too much of a minimal exposure and presence to be actually relevant. It's more a matter of style rather than substance.

I remember that InDecadence's debut, Elephant, is a melodeath album with quite a few post-rock, avant-garde and doom metal influences.

http://youtu.be/CilBLVIiI1o

Omnium Gatherum's latest album isn't influenced by post-rock too extensively, but there's "Soul Journeys" and "An Infinite Mind".