Apple is expected to announce on Tuesday that its next version of its iTunes software will allow users to download movies and television shows in high definition, several websites disclosed Thursday, citing a leak of Apple's upgrade notes. Meanwhile, on Thursday, Amazon announced the launch of Amazon Video on Demand that makes available the company's catalog of 40,000 movies and TV shows for "rent" (i.e., via streaming) on PCs, Macs and other settop boxes like the Sony Bravia TV sets and Apple TV. Movies will cost $2.99 or $3.99; TV shows, $1.99. They can be viewed only during a 24 hour-period after being purchased.