The riser filled at a rate I like, that is after the first jet from the gate. Was your runner full? I can't tell for certain but it looks like maybe it was. I think a blind riser without a straight shot through to the gate (baffle/weir/flow director) will give that effect. I'm sure liking the results I'm getting with a pre-gate blind riser but even so it's not doing anything for the bifilm results. I would think your riser was a better casting than your pattern. Have you calculated your runner velocity? Pretty easy with YouTube's hundredth's of a second count.