Playposit is an online tool for adding interactivity to videos. It has both a free version and a pro version. In the free version for K-12, you can search for videos on YouTube and other video hosting sites but you cannot upload your own. One way around this is to create your own videos without interactivity with another tool, upload that video to YouTube, and connect to that video from Playposit. Playposit has already made templates for interactivity that would be used by many educators making this a super easy tool to use.
Edpuzzle is an online tool for taking existing videos and adding narration, comments, resources, and quizzes. Edpuzzle also has the advantage that it directly works with many LMSs such as Google Classroom and Canvas. Like many of the other online tools, there is a free version and a paid version. In the free version you can store up to 20 videos. In the paid version you have unlimited space.
Screencast-O-Matic is a video creation tool. There is both a free and paid version. The free version is all creators really need to get started as it includes an online screen and video recorder with some basic editing tools. The paid version (about $1.50 per month) gives more sophisticated editing tools. While this tool does not include interactivity options, video creators can make a video with this tool and then use one of the other free tools to add interactivity.
Camtasia, by Techsmith, is a video creation technology that allows screen recording and picture in picture recording, editing for both audio and video, separate narration, effects, and interactivity that includes hotspots and quizzes. Camtasia is a little pricey upfront ($249 for business, $169 for education) but offers maintenance packages with free upgrades or discounted upgrades after your initial purchase.