The very best method to remove grain is avoid it from the get go. Not always possible.
Lighting, independent of the stage lights, and aggressive camera settings.
As for post-production, try Avidemux or VirtualDub for the best filters, then export to a PD-friendly format for final edits and delivery.
HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/BarryAFTT