Seriously? First you introduce the 'est ti' form without even mentioning it and now, when everyone expects it you start with the plural?
The course is great but it could deffinitely use some vast grammar sections in tips and notes.
I would also like some more grammar sections, especially conjugations.
I found this elsewhere (hope it's right and helps):
Mynd (to go)
Es i (I went)
Est ti (You went)
Aeth e/hi (He/she went)
Aethon ni (We went)
Aethoch chi (You went -plural/formal you)
Aethon nhw (They went)
Also Aeth o (He is) in the North.
Aeth e/o/hi are also used for "it" depending on the grammatical gender of the noun.