salaam, I have a question regarding the recitation of duas. I like to listen to lenghty duas such as kumail and josham kabir on youtube. while doing namaz. do i ger sawaab for this or do i have to recite the dua myself.

Walaikumussalam
If one listen the dua will get reward for listening only and when you recite the dua you will get sawab of the recitation, obviously sawab of recitation is higher.
But if you want to listen the dua, either before the namaz or after the namaz.please don’t listen dua while you are praying namaz so you you can concentrate in your namaz .
Wassalam