Again, like the Mot'n vs Mot situation - cai is alternately pronounced as 'cay' or 'cah' - maybe even 'cuh'. It is a significant difference, but there is no indication as to why or when to use one pronunciation over the other. If there really is just one way to correctly pronounce it, then which is the correct way?
You are however completely wrong. The man, who we must assume is a native speaker, is clearly pronouncing the same words in the sentence differently. It is very clear. He dos it both with "mot" where in one instance he adds a "n" to the sound (which he does quite a lot in other sentences too) and also "cai".
Thanks; I realized just after I wrote that (but couldn't get back to it) that I knew what ‘cái’ is. But ‘găng tay’ … if ‘găng’ means ‘glove’ already, then can it be used on its own, or should it always be followed ‘tay’? Can it be followed by other words to mean something else?
Yes. You can use 'găng tay' or just 'găng' for 'glove(s)', 'mitten(s)', 'boxing glove(s)', 'gauntlet(s)' etc. To be more specific, we add more "information" after 'găng (tay)' to show what type of 'glove(s)' we are talking about:
glove(s): găng (xỏ ngón), găng tay (xỏ ngón);
mitten(s): găng (tay) liền ngón;
boxing glove(s): găng (tay) đấm bốc;
gauntlet(s): găng (tay) hiệp sĩ/sỹ, găng (tay) bảo hộ
We tend to use 'găng tay' more because it sounds better when you say a word with two or more syllables instead of one. However, nothing can stop you from using just 'găng' :)
Please also keep in mind that 'găng' and 'găng tay' are of Northern dialects. In the South, people use 'bao tay' instead. Never use just 'bao' for 'glove(s)' because 'bao' means 'bag', 'pack', 'packet', 'sack', etc.
glove(s) - găng, găng tay (Northern dialects)
glove(s) - bao tay (Southern dialects)