A Youtube video from ProfRobBob in which he goes over the General Addition and Multiplication Rules in Statistics. He shows how a Venn diagram can help with the General Addition Rule. He also explains how we started to learn conditional probabilities when we did row and column percents in 2 way tables.

A Youtube video from Daniel Schaben describing how to find the probability of mutually excusive events and non mutually excusive events using the sample space for cards and dice.

This Youtube video from Michael Porinchak covers a few of the basic probability rules including addition rule, multiplication rule, and conditional probability.

Addition Rule of Probability There are many rules associated with solving probability problems. This lesson deals with the addition rule. The addition rule helps you solve probability problems that involve two events. Even though we discuss two events (usually labeled A and B), we’re really talking about performing one task (rolling dice, drawing cards, spinning a spinner, etc.) and finding about the probability of two things happening in that one task.

An excellent tutorial with interactive exercises from algebralab.org