The kind of program you would be looking for is called a 'converter',
to either convert from one format to another or to convert to a
smaller size - sometimes both.
There are several varieties of converters, ranging from the free
simple converters to some that cost several thousand pounds and are
used in professional design.
For this particular solution, a free or shareware converter is the
optimum solution: You don't need exceptional quality, and it's not
something that is financially viable to purchase for just one use.
The Converters Paradise
This site has loads of converters of many different kinds, some free,
some shareware, some demo versions. Looking through the list, I saw a
couple which could be useful to you:
fmp141.zip - The Fast Movie Processor
winsmvid.zip - SmartVid file converter
(Please note, none of these have been tested by myself, so I don't
know if they work or not)
If you specifically want small movies, it might be worth checking out
the DivX codec. One disadvantage of this is that your recipients will
need to download the codec (The piece of software that tells your
computer how to use the software) before they use it.
DivX and Video tools and utilities
Again, I have not tested any of this product, but you might be
interested in looking at AviEdit -
http://www.am-softhome.com/aviedit.html - which appears to do much of
what you require. The product is free for 30 days, and after that is
$25 to register.
I think these programs help you to send your e-mail videos. Please
bear in mind that size is often linked to quality, and that
compressing the videos down from 12+ megabytes to just 200KB will
cause a major decrease in the quality. If your recipient is amenable,
AviEdit will let you split the video up into multiple files which you
can send across a period of time so you don't overload the e-mail
servers, and don't have to upload/download too much at any one time.
Hope this helps!