sorry I haven't looked at this thread since I posted the first response - I am glad you are having moments of success in the training and wanted to comment more to you. First, this forum and the people here are spectacular and the advice I have taken from everyone has been awesome so I want to try to give back a little to you. I never owned a lab either until 18 months ago and I wont lie, there were times I wanted to rip my hair out (hard to do since im bald lol) but the more you put in the more you will eventually get out. I say eventually because does the training really ever stop? There is always something new to do and train to do

I know it is frustrating but I urge you to look at it as a fun activity - training is a bonding session that you get with your dog that is equal to nothing else! Your pup will eventually "get it" and learn. And that is when it feels SOOOO rewarding for your efforts.
I have a post out there in the puppy forums with a picture of my hand. My Jax and his little needle teeth OUCH! I swear my hand looked like a sponge. He was taken from his litter I feel a week early (6 1/2 weeks) and didnt learn bite inhibition from his siblings. That is a mistake I will never make again - I had no idea how important it was to stay with the litter for the full 8 weeks. So my fault equals my extra effort to train him. It took a while. He still "mouths" to this day but is slowly stopping that with reinforced training and some bitter lime spray on my hands and wrists
Overall I think you have the right techniques and information on this thread to get you to the goal you want to reach. Patience is your strongest ally in this no bite training. I would suggest a few more things from watching your video:
- when you say no bite, he actually stopped. At that point immediately say good boy and praise. Correct the bad behavior and when he backs up or stops reward. This trains the dog to understand not only what not to do but also what to do. In the video he did eventually get praised but far after the correction was done. He backed up shy'd away and was told No three more times then got pets. Timing is everything and I think without the proper timing the dog gets confused. For instance <bite> correct with no bite firm voice - <backs off> - good boy and praise.
Make sense?
Also, dont wiggle your toes in front of the dogs face when you are trying to teach him they are not chew toys. LOL I mean come on thats just forcing him to react to the toes!
My Jax used to love biting our pant legs and soles of our shoes too when we walked... he doesnt anymore.
I cant say it enough times, that you just have to continue what you are doing and be repetative and patient and it will fix itself. Trust in that. Its very rewarding to accomplish a training goal and realize your dog is SOOOOOO smart! The lab breed really is a quick learner and desperately wants to please you. You just have to establish you are both the alpha role and the dog is not. Then as training progresses you get to make new goals to train for.
I am currently training Jax to sit and stay when playing fetch and man I thought it was just never going to happen cuz i toss the frisbee or ball and he bolts after it but guess what... lots of time spent and patience, and the last 2 weeks he finally just "gets it" and he sits and stays and just stares at me until I give him the release command of "ok" before he goes and gets the toy. It is an incredibly great feeling - especially when the neighbors see and say "wow, how did you manage to train him like that"
One more thing- are you feeding grain free food? If not, please research the thousands of threads here about it. Grain free food has many benefits but one of particular interest to you may be how the grains turn to sugar and make a dog even more hyper than normal. Grain free is much better overall for your dog on so many levels. Anyhow, just curious
GOOD LUCK DONT LOSE FAITH and most importantly remember this is how you create your bond with your dog - that will never be broken!