Previously, saved probability tables were being inserted, causing the
Vector to increase in size when it should say fixed at a size of 4. This
changes the Vector to an Array<T, 4> which will default-initalize and
allow assigning to any index without previously setting size.
This patch brings all of LibVideo up to the east-const style in the
project. Additionally, it applies a few fixes from the reviews in #8170
that referred to older LibVideo code.
