use Total Video Converter to convert your videos into divx. This software is very intuitive and easy to use.
To get an optimal (at least without applying any filter to the image) use a video bitrate of at least 1500 kbps.
you shoul know that nothing on the internet is safe.
if you are going to download something, try at last to do it from a website like a forum or blog, that have many visitors.
do not download anything from random websites.
at least your TV doesn't support a HD resolution (720p or 1080p) you won't be able to watch them on your tv, i recommend you to encode your fils in 480p (640x480 or 720x480), the best software to do that is Total Video Converter, also is a good option AllOK video converter.