Mobile phone

One of the young ones in our family has got a new mobile phone & wants me to
send her daft things from the PC to it. I found out that I can send animated
gif files & still jpg OK. Are there any other formats I can use? To send
daft things to them, like we have in Flash & Swish. & how do I send mpeg 4?

pmj...

That depends on what Phone it is.

What Make & Model is it?

Some Phones can handle quite a surprising Range of various different
MultiMedia type stuff - not just Animated GIFs & JPEG Pictures.
Some of them will handle various different Formats, such as (some kinds
of) Video Files as well as various different Music (Sound/Audio) File
Formats.

pmj...

See above.
That will depend on what the Phone can handle, what Software you use
to transfer the stuff & what Software (Converters) you have for the
stuff on your PC.

Basically, once you have the File(s) in the required Format that
the Phone can handle, then you Send them to the Phone using the same
(basic) method as you do for any other File Type.

As this is what it uses for music.

pmj...

If you don't have any MPEG4 Files already, you would have to Convert
the Files that you have to the MPEG4 Format. There are various things
around that you can get (some Free, some chargeable) that will Convert
from (& to) MPEG4 format.