As for the first question:
The operation on the laptop might be expensive. Power connectors on laptops are either integrated onto the mainboard or around it. It will require removing and soldering of parts. You can also easily replace the mainboard or applicable part. I recommend
www.impactcomputers.com.
As for the second question:
For video editing, I suggest using another Pentium 4 (P4) or Mobile Pentium 4 (P4m). The Intel Celeron series of processor are designed for low voltage operations. They perform well, but programs such as those that you are using require 'raw processing power' which is simply available in processors with a higher clock speed. If you cannot find a P4 or P4m, AMD's Athlon 64 are formidable processors. For some reason, an AMD64 at 1.8 GHz will perform as well as a P4 at 2.4GHz. However, I suggest sticking with the P4 architecture.