Left Front protest leader Sergei Udaltsov charged the footage was a fake and said he would consult with his lawyers, RIA Novosti reported.
The footage was broadcast last week by NTV, which said it secretly filmed Udaltsov meeting Georgian politician Givi Targamadze to discuss seizing power in several Russian cities.
The men were also filmed allegedly talking about an offer from Andrei Borodin, the former head of the Bank of Moscow who is now in exile, of a $50 million contribution to the protest movement.
Chief Russian investigator Vladimir Markin said Udaltsov confirmed he had met with Georgian nationals this summer to explore legal sources of funding for Udaltsov's political movement.
Udaltsov said he had been "entirely open" with investigators and denied he had met with Targamadze.
Targamadze, the head of the Georgian Parliament's defense and security committee and a close friend of Georgian President Mikheil Saakashvili, called the broadcast "propaganda."
Since Russian President Vladimir Putin returned to power in May, a number of opposition figures have encountered legal, financial or business problems.