I am with some of the others. There are several cameras with amazing optical zooms in terms of how much the lens zooms. But they are all jack of all lens lengths, master at none. There are trade offs when getting these giant zooms lenses. Normally they are ok in the middle zoom area, and gets worse the wider you go, or the further out you go.
And as others have stated a very good tripod is needed without a doubt. The longer the zoom factor the more camera shake will come into play. So much so, that holding it and just breathing will make the camera move! And if your doing video the tripod head is just as important. And since your doing video at a very large zoom, some kind of controlled head is absolutely necessary to get nice fluid movements when panning or moving the camera in general.
To get really good video with any very long zoom, your going to spend quite a bit on a tripod and head. Well more than your camera budget!
Also I don't believe you stated why you wanted such a long range lens for? Birding, or other wild game maybe? That would be a better starting point. What your actually taking pictures of. And can then give better advice on the equipment.