Actor Paul Bettany will go from voicing J.A.R.V.I.S. to inhabiting the persona of the android Avenger known as the Vision.

Walt Disney (DIS -2.68%) needs Paul Bettany more than the studio or most investors would care to admit, Fool contributor Tim Beyers says in the following video.

For those who don't know, Bettany will play the android known as Vision in Avengers: Age of Ultron when that film hits theaters in May 2015. Fans will recognize him as the voice of J.A.R.V.I.S., the near-sentient computer assistant Tony Stark relies upon for, well, everything.

Bettany and Robert Downey Jr. have a particularly entertaining repartee throughout the pair's Marvel movie appearances. Now, they'll appear (presumably) as teammates on a new and growing team of Avengers.

Having him in Ultron is key, Tim says, because the film marks an important transition in the life of the Marvel movie franchise -- the end of Phase 2 and the beginning of Phase 3, when (again, presumably) a new cast of characters forms a new team of Avengers. Bettany's presence could smooth the transition for fans who are loath to see the principals move on.

Now it's your turn to weigh in. What's your reaction to Bettany's casting? How do you see the Marvel movie franchise shaping up from here on? Please watch the video to get Tim's full take and then leave a comment to let us know whether you would buy, sell, or short Disney stock at current prices.