When you say a "rendered video walkthrough" do you talk of something like this ?

If yes LightUp will be fine for you! 😄
It can made even a rendered video walkthrough interactive by the user who has not Sketchup or LightUp !!! 😎
Also for the Net or IPad... 👍

thanks so much for all your help and suggestions. hopefully i can produce something using the tools you have all recommended! much appreciated
😄