There are several studies examining the intake of glyphosate, in many cases even deliberate intakes as a method of suicide. Most of these studies are not freely accessible (behind pay-walls), but in the abstract of the following study, you can find some numbers:
Acute poisoning with a glyphosate-surfactant herbicide ('Roundup'): a review of 93 cases.
- The smallest amount of a 41% glyphosate solution leading to death was 85ml. If I get my math right, this should be about 60g of glyphosate and must hence at least be considered as a potentially fatal amount.
- There are however also reports of ingestion of 500ml 41% glyphosate solution (about 350g) leading to nothing more than mild to moderate symptoms.
I don't have any sound right now, so I am a little but unsure about the amount he claimed to be able to drink. You quote it as 'a quart' (946ml), the subtitles translate it with 'a large glass' and your calculations of the amount of pure glyphosate do not match up.
In any case, since we are roughly within the same amounts that are mentioned in the study: Drinking a glass of glyphosate may give you anything from a sore throat to a lethal reaction.