This is the original intro for the first episode of the first series of Scooby Doo shown on the CBS network in the USA in 1969. They introduced the song theme on the end of the debut episode and at the beginning of the rest of the series. (I had read that this theme without a song was deemed too scary, but it seems that was another of the ‘too scary’ rumours that surround the development of Scooby Doo. (See comment below from a contributor to the Wikipedia article on Scooby Doo.)
This is the early intro for Scooby Doo, Where Are You? with full song. It wasn’t the only version as later series altered the clips used and there were many later reinventions of the show as each generation of children have discovered Scooby Doo, in this and other forms. Just don’t mention Scrappy to fans of the original series!