FR: Spacebar Playback Control

User Story: As a video editor, I want to use the spacebar to play and pause the video on the timeline, so I can have a more efficient and intuitive editing workflow. Problem: Currently, the spacebar does not control video playback. This deviates from common practice in other video editing software and disrupts the user's workflow. Proposed Solution: Map the spacebar functionality to play/pause the video timeline. Benefit: Improved editing efficiency and a more familiar, user-friendly experience.