Pretty sure that if you're suffering from what sounds like chronic lower back pain and you're 99% sure that it's coming from the deadlifts, you don't have 'good form'. Good form would be what works for you, in this case it would be keeping you injury free and lifting heavy ass weights.
That being said, I think its possible you might have a little lower lumbar rounding when you deadlift, at least that's what I suspect from looking at the video. What is you daily life like? Do you sit around alot and do you have a history of back pain/injuries before you started lifting/etc? Answering this questions might give us a rough idea what you're going through? If worse comes to worse, you might have to seek a professional's help.