Your flow is way, way too low. In the video it's just dribbling off the screen. That's problem #1 that I see, that's what is causing the streaking also.
As far as the bubble, it looks more like the water is dripping off in that area, could be that the pipe is not level and as the water builds up a little then it pools and runs out in that area. Adding a gasket around the pipe will stop it from 'escaping' but I think you have bigger problems:
You want 35 GPH
per inch of screen width, basically a sheet of water running down both sides of the screen, covering the entire screen, and you should have a solid sheet of water coming off the bottom of the screen.
I can't tell from the video, but you need to realy rough that screen up if it is not already, or else it won't hold algae very well.
Also review the summary posts starting with #33. I haven't looked at your tank setup, but your screen appears to be vastly oversized. The new feeding guideline is 12 sq in of screen for each cube of food fed per day. Your screen looks like it is something like 16" wide and 12" tall which is large enough (if working right) for 16 cubes of food per day. Unless you're feeding at least half of that, and unless it's lit properly with the right flow and screen roughness, it'll never work quite right.
Bigger is not better when it comes to scrubbers. Size according to feeding, get your flow and roughness right, and provide at least 1W per sq in of screen (LxW) and as much as 2W (split between each side).
Example if you feed 2 cubes/day then you want 24 sq in of screen (4x6) with minimum 12W on each side, or as much as 24W on each side.
If you have the higher wattage, you can run the lights less hours as long as you have a mature screen and all of the light hits the screen (good reflectors or LEDs)