What exactly do you mean by "the back side of the pond will be stuck to the wall...?"
As for glass thickness:
Assuming that you have some reasonable bracing across the top, and assuming the exposed glass and water depth will both be 48" high, and assuming the glass will be 10-feet long, you'll want 31mm thick plate glass.
However, if you use two 5-foot long pieces of glass (and have a strong center frame to hold the two pieces), you can get by with 25mm glass. (In relatively short distances, shorter glass will deflect less than longer glass, so you can use thinner pieces.)
In addition, if you use two 5-foot pieces AND if you have a 48" tall tank, but only keep the water 40" high, you can reduce it further to 21mm glass. (Lower water height reduces pressure on the glass. Just remember not to go past 40" later!) That's likely what is being done in the pond in your video.
So you have some options. However, I would expect that 31mm glass all in one 10 foot piece will be far more expensive than two 5-foot pieces that are 21mm thick. Partly this is because 31mm is 50% more glass and is beyond the capabilities of many glass shops and partly because most glass AFAIK is expected to be 8 feet or less. I don't work in that industry, but don't be shocked at the differences.
FYI, I'm using a 3.0 safety factor.
One other thing to keep in mind, is that if the glass is exposed to routine and wide temperature fluctuations on the patio, it might affect it's strength. I'm not certain of that, but I'd look for more input on that issue. E.g, if the outside of the glass is exposed to 90F while the inside is kept at 78F in the day, and that becomes the reverse (60F and 78F respectively), I'd have a concern that atypical stress may occur inside the glass. Just a question that I'd have if that is what is going to happen.
