I'm not saying don't do it, but it's just not as effective as we are lead to believe and there are way more effective ways to release it (and less painful!) Here's what we know about the ITB
It's connective tissue so has very little contractile properties (hence painfully rolling on it is not going to make much difference in it's length anyway)
It's designed to have some tension to support your lateral quads and hamstrings, so stop trying to make it loose!
How do you stretch it? I like to think of the ITB as guitar string which is controlled by the tuning pegs at the top. ITB tension is controlled by the glute max and TFL (shown below). So if you want to stretch it, grab a rubber ball and start rolling in those muscles. Way more effective and kinder!