Both issues are fixable with free, community-made patches. You do not need to buy anything.
Missing cutscenes and sound in Need for Speed: Most Wanted (2005) usually happen because modern "rip" versions of the game omit the large and SOUND folders to save space, or because the game is looking for files on a disc that isn't there. 1. Restore Missing Files Nfsmw 05 Cutscenes And Sound Fix Download -FREE-