Join Date: Jan 2008
From what I could make out in the video, the majority of your algae seems to be cyanobacteria (blue green algae). This is actually a bacteria, as the name implies, and can be due to several factors (such as low nitrates, dead spots, etc).
As it is bacteria, it can grow very rapidly, and even if you think you have removed all of it, even a little bit can grow back very quickly. You will need to address the underlying problems (mentioned above) first, or else it will keep coming back. In the meantime however, you can manually remove as much as you can first, and then treat with erythromycin to kill off the remainder. I would carefully monitor your fish and your water parameters if you use erythromycin, as the decomposition of the dead/dying bacteria will deplete available oxygen.
For the algae that is on your Vallisneria, it appears to be Staghorn algae.
What kind of lighting do you have? What about CO2 injection?