New lecturers are encouraged, possibly even compelled, to allow themselves to be videoed giving presentations/lectures so they can improve their teaching styles. Even before then, early career researchers may be offered that option and it is probably wise to accept. However, I must admit that by the time I was offered the opportunity to scrutinise my own performance in this way I was sufficiently advanced in my career that I felt that I would merely finally recognize all my irritating tics but be so set in my ways that it would be all but impossible to amend them. So I declined.
We all know the sort of habits that not only we possess but so does everyone else. In ourselves we think so little of them, watching others – say during a seminar – it is possible to get almost mesmerised by their repeated actions. My own failing? Let’s get that out of the way! As my mother, still, delights in pointing out I tend to run my fingers through my hair when feeling nervous. Of course, the end result is, as she so kindly puts it, that I look as if I’ve been dragged through a hedge backwards. Nothing like parents for giving one moral support.
The footage that sticks in my mind is of Prince Charles always adjusting his cuffs as he gets out of the princely car; maybe that is a common habit for men accustomed to wear suits but his is the figure with whom I associate this trait. Or, closer to home, there was my history teacher, who used to pace the classroom covering substantial fractions of a mile each lesson as she expounded on the history of the unions or the start of the First World War. I’m a pacer too, as long as I’m not confined to a lectern mike or wired up in such a way that it ties me down, but I do not believe I cover that sort of distance. But perhaps some student, similarly annoying as I was as a teenager and intrigued enough to work out the mileage, could correct me on that one.
The trouble is that one can get fixated: let’s see when the lecturer next says ‘oh, I say, oh dear’ (another teacher of mine was guilty of that failing). Or the guy who wrings his hands, picks at his tie/teeshirt (depending on style), adjusts his waistband or bends down to pick up some imaginary fluff (yes, I’ve written it about a male, since in physics that is statistically likely to be the sex of the lecturer. You can fill in equivalent habits for a woman, but it probably won’t involve a tie). There are so many mannerisms that we can unconsciously have developed and, if you catch them early enough via that videoing afternoon, maybe you can overcome them. I guess, whether you can or not depends on both motivation and your ability to multitask. By which I mean whether you can give a decent lecture whilst keeping your brain in gear enough in a parallel dimension to say mentally to yourself ‘no, leave your tie alone’.
However, a more fundamental challenge for the new lecturer is often where they should look while delivering their pearls of wisdom. Staring at the screen, with your back to the audience, has its limitations. It isn’t good for audibility, it isn’t good for keeping students’ attention. I’m sure Billy Bunter and cronies would have had strategies for dealing with the master (again, I’m sure he only had schoolmasters) who constantly had his back turned to the class, probably involving ink and/or paper planes; one doesn’t want to find oneself as the butt of that sort of attack. I am sure it is a good idea to look as if you’re looking at the audience, even if in practice your eyes are glazed over or defocussed! Or, my chosen habit at least in flat rooms as opposed to banked lecture theatres, is to look slightly over the students’ heads. That way I don’t have to notice how many have fallen asleep, are snogging or avidly reading a book in preference to listening to my pearls of wisdom.
However, there is one ‘habit’ that I have seen two lecturers of my acquaintance overcome, almost entirely, which I note with immense respect: stuttering. I neither understand the source of stuttering nor how one can work to overcome it. I don’t think it’s at all like working at the lisp I had as a small child, which basically just takes practice and concentration. Since nerves clearly are a factor in a stutter, thinking about the problem is unlikely to be a quickfix. But, as I say, I know two individuals who when first they set out were afflicted severely with this and yet who now are much admired as speakers. Somehow they managed this, which perhaps should give those of us with lesser nervous tics some hope.

“avidly reading a book”?
I think you’re a bit behind the times there! I can’t recall the last time I saw a student with a book. I think you mean “avidly playing with their phones”.
In fact it’s not just new lecturers who are encouraged to be videoed. Increasingly, universities are installing lecture capture systems such as Echo360, and strongly encouraging everyone to use them. The obvious concern is that students will feel they needn’t bother to turn up to the lecture – they can just watch it some time later.
You have a third stutterer amongst your acquaintances. I don’t know if I am much admired as a speaker, but I have sort of overcome it, and part of the story is in this interview with Kathy Weston: http://dmm.biologists.org/content/3/1-2/11.full?ct=ct.
All sorts of ‘cures’ have been suggested. Demosthenes put pebbles in his mouth; I sort of took my speech to pieces and put it back together again.