Language teacher for years Khru Wee (Professor Wee) teaches Thai to foreigners. She also creates regularly short videos, each with a special theme. The peculiarity of her thai courses is that most of them are about Thai grammar and make it simple and understable.
It's educational, easy to remember and you can really understand Thai language works instead of simply repeating phrases and words. The most effective lessons we have found so far.
You can follow Khru Wee on her website