Nobody in their right mind uses cordage like Old Philosopher insists on using, but I have tried to tie friction hitches with that cheap, hard, shiny, translucent, 3-ply stuff that is notoriously difficult to handle and tie knots in. I have some of it that came on a block & tackle game-hoist that I bought on sale at Sportsman's Guide. It worked real well ONCE and then it twisted and tangled itself so badly (with no weight on it to keep it straight) that I had to to replace it with some cheap poly-braid from Walmart.
The original line that came on the game-hoist was stuff that ties ITSELF into knots.....a real labor saver!
Knots that you intend to tie are very difficult to make secure, but it self-ties into knots it takes a serrated knife to untie! When securing the line to an anchor in the shed with a deer hanging at skinning height, I usually just do a round turn and two half-hitches, so I don't use the adjustable gripper-hitch with that rope. It MIGHT work, but I have my doubts......whether it would work with that fancy Amsteel line like you tree-hangars use, I don't know. However, it works VERY WELL with that good 3/8" or 1/2" braided line that you buy off the spools at the lumber yards. That's what I use to tighten the ropes on the ends of the canoe when I secure it to both sides of the bumper, fore & aft on the roof rack. They hold very well and do not seem to loosen any, but I still check them with a good firm pull every few hours of highway travel. If there's any slack that develops, it seems to be from line-stretch due to wet weather.....NO knot slippage.
The reason I don't use a cinch-type knot in securing the canoe is only due to my over-zealous tightening of those kinds of knots.......I once bent the crossbars on a Thule rack by cinching those knots too much!
Our 18.5' canoe on the roof rack of our VW bus, wouldn't so much as shudder when we'd meet those 18-wheelers in the notorious winds of Montana, though!
EDIT:I just noticed the other part of your question and YES, I have tied it 'slippery,' but it produces a knot that is not nearly as good as when tied the way the video shows it. I think that having the two thicknesses of cord going through the bight just gives up too much of the BITE that the knot inherently provides when tied non-slippery. If the pull isn't too great, then the addition of the slippery loop through the last bight may be worth the convenience it provides. If a slippery friction hitch is what you need, then I think the FARRIMOND HITCH is the best way to go......it's a little more 'fussy' to tie, but not much.
And for the new guys that want to learn how to tie the FARRIMOND HITCH, too...here's the thread on that one, too.
http://bladesandbushlore.com/index.php?topic=9854.msg184738#msg184738
