Laboratory practicals are used throughout science and engineering education as it allows students to undertake active learning and develop technical skills. It is therefore important that students arrive to these sessions as prepared as possible to maximise their learning potential. This paper analyses how student preparation affects how prepared they feel to undertake a laboratory practical. It also examines how pre-laboratory video material can affect this preparedness and student marks. Data on student preparedness and preparation is collected via surveys over three years of the same module. Data on video views and retention are collected from YouTube. Findings indicate that students' preparedness increases with time spent preparing, up to a plateau level where further preparation has little affect. Students who watch the pre-laboratory videos increase their preparedness and also increase their assessment mark. Guidelines for creating successful pre-activity videos have been developed and shown to be effective.