While consumer electronics manufacturers have begun offering Blu-ray players free with the purchase of a big-screen HDTV set, Mitsubishi said Wednesday that it will offer instead a Vudu settop box, allowing purchasers to stream or download thousands of movies and television shows, many of them in high definition. They will also receive $50 in credits. (Rentals are as low as 99 cents; downloads start at $1.99 for TV shows; $4.99 for older movies; a download of a new release runs around $19.99.) Other manufacturers are building similar systems into some of their models, eliminating the settop box. But Frank DeMartin, head of marketing for Mitsubishi, noted that the distribution of movies over the Internet to TV sets currently involves different competing platforms and that a shake-out may be slow in coming.