This is a true polyglot

It's like that Russian is the worst among all of his languages. He made a long pause, couple of mistakes and his pronouciation is far from perfect.
May be that's because he learnt it only for 3-4 months and not in Russia...

But in general, that's amazing :)

Czech is only west slavic language, he spoke and these are only slavic languages that I know; like I said he pronounce well, used correct declinsions... but he has a weird accent and had to stop and put the sentences together in his head instead of speaking through instinct...

He seams best at Romance languages (the ones he has studied the longest) and good at Germanic languages (the family of his native languages), but I would say for his limited study he does well with the Slavic as well.

Small mistakes in Dutch. But I could understand him without any problem. We have the weird thing that if something is 'several years', we still use the singular form..
He has worked for several years in my country. (Don't know exactly anymore, as I listened to him a few days ago, and I don't have sound here at school)

But in Dutch it's: Ik heb drie jaar in Roermond gewerkt. (just an example).
Litt: I have three year in Roermond worked. (Year is singular, where it should be in plural..)
He said something like this:
Ik heb drie jaren in Roermond gewerkt.
Litt: I have three years in Roermond worked.

Now you'd wonder why we still have a plural for 'year'. The plural is used in cases like: I've worked some years.
Ik heb enige or enkele jaren gewerkt.

I don't know if the following is correct, but we use it very much. We all know 'a pair' is plural. However I'm used to say: 'Ik heb een paar jaar gewerkt'. And all other Dutch people I know say that as well.

Even though I'm Dutch and I hear and say this sentence almost each day, it feels very wrong to me.
To me it would be more correct to say: 'Ik heb een paar jaren gewerkt'.

Someone who can explain this?

His Spanish pronunciation is 100% native. Amazing

Interesting video. However, I wouldn't know how "polyglot" he is in all the languages he affirms to know.
Is he a polyglot that can have a basic conversation in all the languages? That would be still a heck of an accomplishment. I just wonder how many languages he's mastered to the same level of his native language.
Regardless of the answer to these questions it's an inspiring video, even though I wouldn't study half of the languages he has studied because they would be useless to me since I'm in Japan and this is the last place where the knowledge of languages is valued.

Cheers,

J.

p.s It would be really amazing if he spoke in an asian language.