Almost all discussion is liable to break down unless we define happiness.
However, on a gut-level, I think I know what is meant. I would ask this: if this is not a thought experiment, have you made a habit of experiencing this happiness? Ie. have you trained yourself to expect the happiness? If not, it might "simply" be your ingrained habits reasserting themselves, and the happiness/unhappiness difference not being great enough to jolt you back to happiness.
I think there can be several possible reasons for why people do not do the thing that they know will make them happy, and here the definition of happiness really does become crucial.
I guess what some of the other comments are aiming at, is there a categorical difference in whether you watch something because "people crave for meaning" and "people crave for rewarding experiences". The latter is the lever exploited by facebook's, instagram's or candycrush's design. Is there a difference when people go hunting for a philosophy of life? The search for a personal guru? I'm not sure. If what makes you come back again and again is the dopamine high you get as part of the experience of finding an inspirational talk, maybe that's not a search for meaning. If the reason you are coming back is a different kind of reward, maybe it's more likely to be motivated by a search for meaning.
Very good idea, and it hope you make it!
Apart from the obvious "theoretical" or foundational topics, I recommend focusing on making it crystal clear how rationality can benefit "normal" people in everyday life, with examples. Especially in the beginning. I think we all know what most people associate with words like rationality. To get anything of worth out of anything non-trivial, people need to invest quite a bit of energy, and the best way to ensure that is to make the potential benefits very clear and enticing.