Could this be Jim's Gift: Fastforward the Future?
There is a very obscure movie called Jim's Gift, released in 1996.
It was based on an even more obscure novel by an equal obscure author named Sylvia Wickham, written in 1994.
According to the movie description:
When Jim gets home, he tries the VCR, which has an interesting feature: Jim can see events from his past—from birth to just a few moments ago. He uses this to find some lost money and the like, leaving his parents thinking he's psychic. Soon Jim finds Bossy, but he's not done with the VCR. Naturally, he won't be able to resist pushing that fast-forward, and when he starts trying to foil robberies that haven't happened yet and picking horse races, there's trouble. When trouble hits, the stranger repossesses the VCR, which means Jim and a pal must solve a mystery themselves.
I can't find any book description.
There are some IMDB reviews here that offer additional details.
This fits several of the criteria, assuming that the book is similar to the movie:
- It was published in the early 90s (1994), and features
- a VCR that
- can record the past and the future and
- probably is controlled by buttons, not dials (to judge from the book cover).
- The main character is a boy.
- It is 96 pages (under 100, though not under 50).