I was just watching the clips of The muppets "Are you dating" Video on muppets.com, I noticed that Fozzie and Piggy were done buy Franks voice.
My Question is: Are these clips old or has Frank lent his talents to the muppet again.
anybody know?
Short answer: These clips are old.
Long answer:
The clip that you are speaking of is filed under "The Muppet Show - Season 2" and listed as a "DVD bonus" clip on Muppets.com. The clip is in fact an excerpt from "The Muppet Show - Season 2" DVD box set -- it is specifically taken from a 13-minute bonus feature entitled "The Muppets on Muppets".
The interview segments were produced in the late 1990s for the Odyssey Channel, however they were never aired and were not seen by the public until their release on the season 2 DVD in 2007. Frank Oz is performing Fozzie and Piggy in the clips, but they were film 8-9 years ago, back when he was still the primary performer.
So those DVD preview clips (including clips from several season 2 episodes, plus the Weezer music video and "The Muppets on Muppets" bonus features) are all old clip that were produced prior to the launch of the new Muppets.com...However the other videos on the Muppets' DxD site are all brand-new and created just for site.
So to answer your question, Frank is not working with the Muppets now - Eric Jacobson is the principle performer of Piggy and Fozzie. Frank's last known work with the classic "Muppet Show" characters was on The Today Show in 2002.