Summarize this article in one sentence.
You'll need the latest version of Snapchat in order to access the video chat features. The new video chat was introduced in version 9.27.0.0, released March 2016. You can check for updates using your device's app store. Video calls are not available in all areas. Video calls are placed directly from the chat screen. You can only make video calls to other Snapchat users.  You can open your recent conversations by swiping from left to right on the main Snapchat screen. Swipe a conversation from left to right to open it. You can also tap the "New Chat" button in the upper-right corner and then select the person you want to call. If you haven't done this before, you'll be warned that video calls will use mobile data if you aren't connected to a wireless network. The other person will be notified that you're calling them for a video chat. If they have notifications for Snapchat enabled, they'll be notified no matter what they're doing on their phone. If they don't have notifications enabled, they'll only see the call if they're currently using Snapchat. You may get a "Busy 😫" message, indicating that the other person is not available to receive video calls at the moment. The recipient will be able to either just watch your video, or join the conversation and share video as well. If you're receiving a video call, tap "Watch" to see the other person but not show yourself, "Join" to join the call and send video back, or "Ignore" to send a "Busy" message. You can switch between your front and rear cameras at any time during the chat. Tap your video to make it full screen, then tap the camera switch button in the upper-right corner. This will let you use your phone, but it won't hang up your call. Tap it again to resume full screen. This will not actually end the connection. You'll still be able to see and hear the other person until either they hang up or you close the chat. You can close the chat by switching to another Snapchat screen, switching apps, or closing Snapchat. You'll see a small circle appear while you hold the button. You can record a message up to ten seconds long, and it will play when they open the conversation next. You can cancel the recording by dragging your finger to the "X" button.

Summary:
Update Snapchat. Open a conversation with the person you want to call. Tap the Video button to place a video call. Wait for the other person to pick up. Switch the camera you're using. Swipe down on the video to minimize it. Tap the Video button to hang up. Press and hold the Video button to record a video message.