Wow, that’s pretty brave, I’d never find courage to learn a language by making public videos as I go along.
I am not myself a native (so take what I write with a little grain of salt), but I am a Polish speaker, and I can communicate in Czech.
Overall pretty cool, and your pronunciation sounds quite good, definitely understandable. Very good observation about people pronouncing syllabic /m/ as [um]. Although most textbooks will teach you to say it as [sɛ.dm], without any vowel in the second syllable, I agree most speakers actually say [sɛ.dum].
A few times your -t at the end of words to me sounds a bit like -c, as if you read eg. *pěc
(with affricate [ʦ]) and not pět
(with stop, [t]). Also you’ll need to work a bit on those š vs č vs ř in consonant clusters (like in čtyři
, yours sounds a bit like *štyrí
As for the grammar, you subtitled your video as jedna lekce
, this is grammaticaly correct and means ‘one lesson’, ‘some lesson’. But I believe what you meant is rather ‘first lesson’ and that would be either první lekce
or prvá lekce
(the ordinal number ‘first’ has two forms – soft, more common, první
, and hard, a bit more archaic, prvý
Anyway, pretty good start. Good luck with learning.