Hi there and
to the forums!
Even with multiple food bowls at the same height in the cage, some budgies always think the grass is greener!
From the video you posted, it doesn't seem like Sarge is too bothered; he just moves and lets Grif eat from that bowl. If this is usually how it happens, and Sarge doesn't seem affected or injured/bullied to the point where he is stressed out, then it's not as big of an issue.
However, it could potentially develop into something more aggressive, so it's important to try and discourage this by either feeding them separately (which may be difficult, given that they're so close otherwise), or trying different locations and types of feeders, which may discourage Grif from going after Sarge. For example, a feeder at a slightly lower or more secluded part of the cage may feel less desirable to Grif.
The screech noise Sarge makes is a frustrated screech, like saying "Stop it!" Surely he does get bothered by never getting to eat in peace! I hope you're able to find a solution that works or lessens his response towards Sarge; perhaps other members will have other ideas as well.
Meanwhile, it's good to hear you've been reading through the forums! If you have any other questions after reading though all the basic links, be sure to ask as we'd love to help!
Hope to see you around