There are two movies related to your query:

1. "Witness" (1985) is a thriller drama about an Amish child witnessing a murder. It stars Harrison Ford and is available for streaming on platforms like Paramount Plus, MGM+, Philo, Amazon Prime Video, and others. It can also be rented or bought on Amazon Video, Apple TV, and other services.
2. "Can I Get a Witness?" (2024) is a Canadian sci-fi film blending live action and animation, set in a dystopian future where people must end life at 50 and teenagers document it. It stars Sandra Oh and premiered in 2024. It is available for premium video on demand on Apple TV, Amazon, Rogers, Crave, etc. It also plays on Air Canada flights and at some upcoming film festivals.

Please specify if you want to watch "Witness" (the thriller) or "Can I Get a Witness?" (the sci-fi), so I can provide details on where and how to watch it. Both are currently available for streaming or rental in various platforms.