Caveat: I haven't watched the video (sorry!) so this may be covered there.
Fields: yes, totally. Lakes: MUCH iffier for solar. Floating solar has been a bit of a pipe dream for quite some time now. Not saying it can't be done! But the biggest issue is that water+electricity is very tricky. Water (not purified) is conductive, as are the bodies of little critters that want to crawl all over the sudden islands now in their habitat, and it usually doesn't go great for them or your electronics. Water can be corrosive, and what do you do if your lake is in a location where it will freeze in the winter?
Where I think you can go well with combining solar and water: canal "roof" style (well above the water, the sun there not really used for any other purpose, allows animals to access water, prevents water from evaporating). I think there is a place for floating solar to combo with dams (often a water supply you don't want evaporating too quickly, you've got your electrical hookups right there, the dam itself is essentially a giant battery) but you have to solve the electricity+water issue somehow (raising it up like a big floating parking garage has been considered, maybe something like that?) before I think we start seeing it rolled out.
Fields are great for so many reasons- easily accessible for installation/maintenance/emergency services, pretty abundant in the US, fairly close to where people are, gives rental income to farmers who may be struggling, etc. Many times solar farms can be used in conjunction with conventional farming, usually under the blanket term of "agrovoltaics".
One of my favorite ideas for places to put solar though is retired golf courses- already fairly flat with paths for vehicles, cleared of trees, near people, can't farm on it due to the chemicals used to maintain that specific grass, etc.
Solar is only growing in the US (and hopefully the world) in the next decade! It's great to think about what novel places we can plan to put it to maximize access and utility for everyone (including distributed grid options).