Karthik R
Hello Apologies for the delayed response on this. The source term in Fluent is a volumetric term. Which means that if you integrate the provided value over the cell zone volume, you should get the desired power in W. In other words, if you integrate the constant power source of 392000 W/m^3 over the cell volume of the corresponding cell zone, you should get the correct power loss provided by Maxwell. This is what is being done in the video.
If you are looking for some additional information, please take a look at the following link from the Fluent user's gudie.
If you are looking for additional tutorials on coupling Maxwell-Fluent, please have a look at the following links. You should be able to download the files as well.
If you need additional instructions on how to access these links, please see the link below.
I hope this helps.