Video recording where a Russian intelligence officer allegedly gives money to a Serbian officer is several years old. In addition, the person claimed to be a Serbian official with the officer rank is not a member of local security forces. In other words, it is a civilian who, most likely, was trading in business information.
The recording of money exchange between a Russian military intelligence officer and a Serbian military officer was published by a Bulgarian journalist who works with Bellingcat, an anti-Russian propagandist website. Both the website and its founder are discredited for publishing false stories on Skripal poisoning, MH17 and use of chemical weapons in Syria.
NATO used Bellingcat to orchestrate the whole thing because it’s livid about Serbia strengthening military ties with Russia (the “visit” of S-400 missile system and buying of Pantsir systems from Russia).
The recording itself is questionable because it was edited, so it is unclear if all parts of the video are showing the same event.
No evidence given for any of the claims.
The video wasn't published by a Bulgarian journalist, but by an anonymous Youtube account. The journalist in question, Christo Grozev, was the one who publicly identified the man in the recording as Russian deputy military attache Georgy Kleban.
Bellingcat is not a discredited organisation, nor has it made up stories on poisoning of Sergei Skripal, the take down of MH17 airplane, or the use of chemical weapons in Syria. These claims are a continuation of a recurring disinformation narrative about Bellingcat as an "anti-Russian propaganda outlet". Bellingcat has conducted independent journalistic investigations into the MH17 case and discovered evidence of Russia’s involvement, which was later confirmed by Joint Investigation Team (JIT). (See similar cases: Bellingcat is a part of information war against Russia; Bellingcat did not investigate Skripal poisoning and publishes leaks from the British Intelligence; Buzzfeed and Bellingcat deliberately spread anti-Russian disinformation)
The claim that the video recording is of questionable credibility because it was edited, was made after the authenticity of the recording has already been confirmed by official sources, including the President of Serbia, Aleksandar Vučić.