An older friend of mine regularly comments about people watching videos on their phones and the screens being far too small.

Personally the size of the screen doesn't bother me, it's just great to be able to watch something when on the train or a bus. I'm using my phone more and more for the Internet, I've not used my laptop in ages.

YouTube? Yes. (That, and my addiction to Facebook, is almost certainly responsible for my need to wear glasses.)
Catch-up? No - that's pretty much the only thing I use my tablet for.

On the iPad I do due to its big screen but I only view catchup unless it is Question Time or something like that. Youtube, LOL! Far too much.

I sometimes watch Sky Go, YouTube, Netflix on my phone. Not that often, but if I'm bored when out and about.

The screen size is not ideal of course, but it will do.

I have just a plain mobile, so no.
But, I do have an iPad mini.....and this gets a lot of use. Short videos, yes.
But I would never use it for watching a full length film.......I mean, seriously on that little screen, with those hopeless speakers.

No, they drain the battery and my data allowance too quickly.

It would have to be something pretty exceptional.

I might if there was a free wifi hotspot close by, that I could use - and if it's got a password, that the sodding thing is actually on display somewhere.

People are replacing tablets for larger phones (some now only an inch or just over smaller than a small tablet) so don't be surprised if a lot of people say yes even with lowering data allowances and rising prices of data and phones as companies capitalise on the growing popularity of smartphones and make up for falling tablet revenues.

I watch YouTube occasionally on my phone, but for web browsing I'll use a laptop. I have a few mobile versions of websites bookmarked on my phone (including these forums) but generally speaking phones are the worst device you could use to browse the web. I only ever watch Netflix on my TV.

I still love my tablet. Find it far easier than the phone, to navigate the web.

I don't want phones to be too big to carry comfortably in the pocket.

As for mainstream stuff, I use a chromebook, which replaced the old PC.

I mainly use my iPad, my iPhone se is a bit small for videos, I'll use the phone if I really have to.

Not really possible as I have a basic Nokia that does text messages and phone calls but if I had a smartphone, no, I wouldn't use Youtube like I do on the laptop and catch up tv is catered for by having a NowTV box.

Sometimes I do but I tend to use my Macbook for watching Youtube videos. I don't use catchup TV much but on the occasions that I do I'll use my Mac.

No, it would never occur to me.

No, not really.

Out about I only really ever use my phone's online capability to quickly check something. Mostly things like directions, shop opening hours, bus times etc. Sometimes I might also check a wiki article or find out a fact if conversation or something I see/hear makes me curious about a topic.

The only time I'll really go online at all on my phone at home is when I'm already watching something on tv so there'd be no need to watch it on my phone. Then it's usually quick fact checking too. Watching football, a player comes on a sub, I might be curious where they signed that player from or what country they come from etc. so I reach for the phone. Watching something about history, a historical figure might be mentioned and I may wonder when they were born/died etc. Stuff like that. Outside of that, if I'm online at home like now it will be on my PC and I watch lots of Youtube on here.

My phone stays in my pocket mostly all the time when I'm outside. If I have to use it I stand still but I'll never use it when talking to people in person.

Only when I can't be bothered to turn the tv on or I'm going to go to sleep but just have to watch this youtube video.

The thing to think about is the how much of you field of vision the screen takes up.
A 40" TV viewed from 3 metres is roughly as big in your field of vision as a 7-8 tablet at a comfortable arms length so why not watch a TV show or film on it?
A smart phone, which always seems to be held closer to the eye than a tablet, is probably the same with a 5" screen.
Sound quality is an issue but then you can wear headphones. Comfort is another issue. holding a tablet/phone for the length of a movie is a bit of a pain in the arse, but for short Youtube videos they're fine.

Yes, I watched most of the recent one day series between Australia and New Zealand on my phone. Work wi-fi so no data charges. Looking forward to the test matches starting soon.