There are only young Thai generation don't know their own language were came from Lao language. Lao alphabets were born before Thai's then Siam copied from Lao then mixed with Kmer, Bali and Sansakrith.
This Thai guy try to tell Thai people the their language were came from Lao.
This all true all thai siam language just creat in all lao words for 200 years ago. There is no such thing Thai Siam had has their own language from their ancestor. if there is no lao in this planet, there is no thai siam because lao and chinese the old people in asia and southeastasia.
Thai, Lao, Lanna, Shan, Tai Lue, Tai dam, Phuan etc are all from Southwestern Tai language family. Thai has a lot of Khmer influence. Shan has a lot of Burmese influence. Lanna also has some Burmese influence. Tai Lue today has a lot of Chinese loanwords. Tai dam has Vietnamese influence. And today our Lao language also has influences from other languages too! We are Tais. We conquered Khmer(khom) empire, so we should be proud!