Happy tying & stay warm!
Tim Flagler: Tightline Video : A wide range of patterns that are well organized, with clear, concise instructions. Tim also has OVER 200 tip's & technique videos which are sponsored by Orvis: Tim's tips and techniques
Davie McPhail 1.4 THOUSAND videos! Davie is probably one of the top fly tiers on the Internet. His fly's, technique and instruction are immaculate. A level to aspire to. Mostly pattern based, but also some tips etc.
Slide Inn : This is Kelly Galloup's Fly Shop/ YouTube Channel. Montana based angler, who helped change the game on fishing for big trout with big streamers. Kelly is also a fantastic dry fly, nymph and wet fly tier/ fisherman. Videos are pattern based, but Kelley explains nearly every step, which can lead to some long but information PACKED videos.
Fly Fish Food: Utah based fly shop with great videos. Pattern based but they also have an on-going series of fly tying "hack" videos called Skill Builder where they will talk about short techniques, skills and hacks that you can use to be more efficient in fly tying:Fly Fish Food Skill Builder Series