Blink customer support can restore deleted videos, and even tell you who deleted them.
My wife and I both have the app on our phones, and I discovered that my clip roll was disappearing every couple days. I called customer support, and they were able to identify the phone model that was deleting the clips. Needless to say, it was my wife deleting them.
submit a support ticket for them to restore the videos (don’t worry, they can’t view the clips. The videos are encrypted with a unique key that’s assigned to your account. They do not have access to that.)