You can actually handle this feature using three methods; through the web, through Android, or allowing Google to automatically decide which videos need enhancing.
Below are the steps;
Web
Step 1: To locate your video on Google+, click the left-hand menu and head to Photos. Once there, click More in the menu along the top and select Videos.
Step 2: Open the video you want to enhance, and click More (again) at the top menu. Choose Auto Enhance from the menu.
Step 3: You will see a side-by-side comparison of your video before and after enhancements. If you like the changes, click Apply at the top and your video will be processed.
Android
Step 1: Open the Photos app on your Android device and tap Videos in the slide-out menu on the left-hand side.
Step 2: Select the video you want to work with. Tap the overflow menu (three dots) and choose Auto Enhance.
You will see the Enhancing tag near the bottom of the screen to show that it is processing. Unfortunately, you cannot see the same side-by-side comparison like you can on the Web.
Automatic
If you want the enhancements to happen automatically, make sure that Auto Enhance is enabled on your Google+ account.
On the Web, click the left-hand menu > Settings > fill in the bubble next to the Auto Enhance strength you want to use.
On Android, tap the overflow menu (three dots) > Settings > Account name > check the box next to Auto Enhance.
