Just because “a lot of people believe” something doesn’t make it true. There is no public evidence that WikiLeaks is in any way affiliated with Russia. There is public evidence (and sound logical argument) that data WikiLeaks released about the DNC came from an inside source.
Also whatever the intentions of the video they said something specific. They made a specific claim in unambiguous language. They need to change that or it stands as a falsehood they said.