Promos

I have been looking at promos on youtube and it looks like most of them are film based showing clips of the tv shows. now if i don't have to actually make it i could do that but I'm not sure as that what everyone would do.
Here are some examples:
https://www.youtube.com/watch?v=NDYHBOOu61o
https://www.youtube.com/watch?v=OqLCI6MkVfA
https://www.youtube.com/watch?v=XYYgLcaz1oA

I have also looked at some idents but i don't think thats what they're after as idents don't promote anything they're more like space fillers.
Itv's seem to be very film based and simple with just someone talking over the top which is more than some 
https://www.youtube.com/watch?v=5izR0EEgmbk
Like comedy centrals idents, although they're fun and creative which is good because its a comedy channel, they don't actually advertise or show what is on the channel.
https://www.youtube.com/watch?v=VqCMuogovkI