It's a strange thing, because all my students are good at getting submissions... but most of my lessons I just teach something about control or passing, sweeping, defending, fundamentals of a position etc. Then in the odd class I will throw a submission on the end.
My thinking is that if position before submission is so important, why ignore that when teaching? If people can get to dominant positions easily, they'll quickly be able to learn how to submit people easily whether you show a new technique every lesson or not. There are lots of movements and positions and transitions in jiu-jitsu, but there aren't that many different ways to submit someone... there are lots of variations, but not many fundamentally different ways mechanically. There are definitely lots of minor details which will make a difference to whether you finish a submission or not, but in the overall scheme of things, knowing the minor details of a sweep or pass is always gonna be more useful and more likely to help more students overall. Everyone body shape and size can use butterfly guard well, every one can use pressure passing... but not everyone will benefit from another triangle lesson... nor arm-triangle lesson. Everybody ends up in half guard, no matter shape, size or game, but not everybody ends up going inverted to a toe-hold (although all that stuff is effective and does have it's place :) ).
Actually, submissions are probably the easiest thing to learn from instructional videos. If you can get regularly get dominant position on training partners you can easily practice stuff you've seen in a video. It's much harder to learn how to control and move in a certain position from just watching a video and not having instant correction from an instructor.
My instructor, Chris Rees, taught me the same way... he used to show me how submissions worked by wrecking me with them all the time haha. The vast majority of my wins in competition are by quick submission.