Perhaps the best thing to come to the Overwatch League for fans yet, the new Replay Viewer will allows players to access replays of past matches, with a number of different viewing and recording options available. Read more about the launch here.
How to access the Overwatch League Replay Viewer

Instructions
At this early stage, the Overwatch League Replay Viewer is only available to PC users. Here's how to access it.
- Download (if you haven't already) and then open the Battle.net app.
- Click on Overwatch.
- Navigate to "Region/Account" drop down, and select "Professional Viewer".
- Smack that "Install" button.
- Click Play.

Hotkeys
Blizzard has also introduced and detailed a number of keyboard shortcuts to help you navigate through the Viewer.
- N: Show/Hide controls
- W, A, S, and D: Move the camera around
- Q and E: Move camera up/Down
- Scroll Wheel Up: Increase playback speed
- Scroll Wheel Down: Decrease playback speed
- CTRL + P: Play/Pause
- Spacebar: Toggle between first-person and third-person view
- Left/Right Click: Detach from first-person and third-person view to free camera
- F1-F12: Spectate players (corresponds with player list in media controls)
- 0: Snap to the objective
- CTRL + I: Show map overlay
- CTRL + 1 through CNTRL + 9: Save bookmarks
- 1-9: Restore camera bookmarks