I work with kids with Autism and I think going TV free is great, you may even see a reduction in his behaviour after an adjustment period because he may sometimes throw tantrums because he knows in the end that he will get the tv to calm down, or he is just a routine for him (or you may not see a decrease as well if there is no relation).
Some ideas if you can get some books - Pivotal Response Treatment for Kids with Autism by Koegal - it is a really good way for parents to be able to play "games" with the kids and teach them at the same time. Also Building Bridges through sensory integration is good and so is More than words for specific "games" or interactions you can have with them.
All of these are things that you have to do with him as play skills for our little guys is hard to do independently.
I have heard Relationship Development Intervention is really good but is hard to follow through the book and floor time is excellent for teaching playskills but very involved.
As for a quick and easy distraction from melt downs, going for walks sometimes works with some of my kids, or sometimes they have a particular thing they like - letters, numbers and playing with these helps. Sometimes just having a routine works - so having balloons in the same place and he goes with you to get one, picks one out, you pump it up and go to a particular room and he plays (you can also incorporate some of the games from the books mentioned in the balloon play) - and going through the routine is very calming if they are starting to get anxious.
There is a huge reduction in tantrums in kids who learn to communicate (either with words, sign or pecs) so you might be able to start reducing the melt downs by working on his communication, though this isn't an quick and easy fix hopefully it will help with knowing that one day you might be able to have few or go without melt downs.