Zeedman
Garden Master
Good point about the reflective sides. You also have gaps at the bottom to allow convective air flow.This is after they have grown some. I adjust the light height with that chain, trying to keep the light within a couple of inches of the top of the plants but some grow taller than others. To try to stop the plants form getting too leggy reaching for the lights I hang white paper on the sides to reflect light onto the plants from all sides that I can. That reflected light makes a lot of difference in how leggy they get.
I agree about maintaining sterile conditions. Most soil-less seed starting mixes can be considered to be sterile, although they are seldom labeled that way. I've used the ProMix mentioned in the video, and it worked well. It is also not a bad idea to use sterile water for the initial soaking, until seeds germinate.