Steve, let me address some issues because I feel like we're stuck in a loop here.
1. The video. I don't know if you read any of the comments in this thread but a lot of time and effort went into analysing the video, pointing out what was wrong with it and establishing what it really should have been about. No one who has read these comments would feel the need to stress that it's not the most helpful resource in the world. If I hadn't found it questionable, I wouldn't have posted it in the first place.
Neal was the first one to confirm that there were times when the "try to" and "try doing" sentences were interchangeable. He also felt that the teacher was deliberately choosing a limited range of examples to make her argument stronger. Did you read his comment? SuKi explained that in some contexts there was no real difference, while in others, one was more preferable than other. We discussed this at length and looked at different examples. If you have anything to say about the examples we used, please do so because I'm always interested to know whether the things I've learnt sound natural in other English-speaking countries as well as in the UK.
2. What learners should or shouldn't learn. This is very individual, and, as I expressed in my comment yesterday, not something one person should decide for everyone. Some people are genuinely interested in taking exams, quite many actually. Some people want to be able to read and write academic papers, existentialist novels, poems, what have you. And, of course, some just want to be able to communicate but there are no universal resources that would work for everyone, nor can you expect every single teacher to create those. A good teacher teaches students what's relevant to them and not what's relevant to "the majority who aim low".
3. About colloquial language. I am glad that we're embracing colloquial language here. I teach my students both standard and common Czech (if they say they want it this way) because using the wrong style at the wrong time can have all sorts of negative consequences. However, if you're using your target language and you overdo it (your language is "too colloquial"), you make yourself sound totally ridiculous. Remember all the "gonna" and "wanna" posts on italki? I don't think that plain, textbook-like black-and-white English could ever be source of this much embarrassment. Not everything you say, as a native speaker, will sound the same if I say it.