what's with the backwards movement sometimes

SourceRuns Wiki articles about the most used glitches in the run:
http://wiki.sourceruns.org/wiki/ABH
http://wiki.sourceruns.org/wiki/Teleporting
http://wiki.sourceruns.org/wiki/Flying
http://wiki.sourceruns.org/wiki/Stucklaunching
http://wiki.sourceruns.org/wiki/Edgebug
http://wiki.sourceruns.org/wiki/Wallclimbing
..visit the wiki itself for more articles.
first link explains it
Accelerated Back Hopping (ABH for short) is a Glitch, and it's the main method of transportation on OrangeBox Engine-based games. ABH totally replaces Bunnyhopping, which was fixed in the OrangeBox Engine. Also, it's much faster than Bunnyhopping.

I can't believe that ABH thing is even possible. The Valve guys tried to fix bhopping without even thinking of the most obvious way to bypass that fix...

Oh well, it looks even more baller now than on older runs.

pretty ridic stuff indeed
some of the tricks and skips done ive never even imagined

Speed-runs are awesome! http://speeddemosarchive.com/ ftw baby!

"The water scooter" collision jumps are awesome

crowbar only, hard mode, done in 40 mins

well that ruined quite alot of good memories from what I first played hl1 :D

meh, looks super clunky and the cutscenes/set pieces kill the pace so often

doesn't hold a candle to HL1 and Quake1 speedruns. those were smooth and fun to watch

speed runners delight pack, quake 1 co-op speed runs are still my faves!

http://speeddemosarchive.com/quake/qdq/movies/rdsc.html

some 4 player and i think (?) 6 player runs are about too.

I feel violated after watching that. Geez.

41:47 I came

He peed himself while running?

There is also downloadable version in the youtube video description which includes a commentary track. It is highly recommended.

While the cutscenes are indeed boring and take away the pace, it's not easy task to make all those NPC teleports perfectly. In the commentary Matmo says that he was trying one of the cutscenes over 8 hours before he could make a satisfying run.

Compared to something like Quake done quickest where you can just compile all world record runs into a single run, in this speedrun it's a team effort where everybody continues with the same health, weapons and velocity from the previous segment. And obviously you can not go back, unless you record everything again from that point.

They will also make another commentary which will be really detailed about how everything was made.

the run is incredible

Can't believe I watched an hour of this and wasn't bored for a second.

Some really slick moves thrown in there.

so can you use these techniques in other orange box games?

cool action movie

All this running back looks fucking silly, but I have to say, surfing on a barrel through air was one of the most awesome things I have ever seen.

Also, on that note, something Quakers will be a little more familiar with:

there's a 22-24mn long version in the work ;)
Can't wait!

http://www.youtube.com/watch?v=zhK3QwDVweA