We developed a prototype called SeeSaw that explored using reaction video and auto reply to create an engaging video messaging experience. When viewing a video message, reaction video captures a video of the viewer’s reaction to share back with the message sender. After finishing viewing the video message, auto reply immediately begins recording the viewer’s response. A pilot study found that SeeSaw evoked conversational and authentic interactions, even though the messages were captured remotely and asynchronously. A follow-up comparative lab study found that reaction video encouraged a more conversational exchange, while both features together enhanced the authenticity of the experience. Although participants preferred the reaction video only condition, they perceived that the reaction video plus auto reply condition combined the conversationality of a video call with the flexibility of asynchronous messaging.