Can anyone tell that how to detect PCB’s through video capture using python.

I think this question as such is a bit out of scope on this forum… One way to find methods and tools (including Python tools) for this is to search for “PCB defect detection papers with code” which will give you many references to academic papers + code (on the https://paperswithcode.com site).
For instance: ChangeChip: A Reference-Based Unsupervised Change Detection for PCB Defect Detection | Papers With Code