I tried 'Internet Download Manager' and I liked it so much that I bought the program.
I have so much faith in it, that I never bother with the Hash thing. When I download a program from a known good site, I just know it will work. So far, I've never been wrong.

Then I use top quality DVD's and a top quality DVD Burner, run at the slowest speed and I never get a bad burn.
Old saying, "do it right the first time and you won't have to do it over". Just a thought.

Cheers Mates!