how can i get mp4 from the internet onto my ipod touch
Right click the link in your browser and save it in a place you can remember. Open finder and locate the mp4. Right click the file and click Open With > iTunes. You can also drag the video into iTunes if it is already open. Then you can sync the video by plugging in your iPod and selected it under "Devices" in iTunes. There is a tab for videos and you can select which videos from iTunes you wish to sync (just like music).

Alternatively, you can visit the link in Safari on your iPod and stream the video, but you would of course need an internet connection.