TICL conference I gave a short presentation about classroom video projects. Part of that presentation is a short list of things to consider when planning a video project.
1. The first consideration is what you want your students to demonstrate through their videos. This will help to determine which video production tools your students will use. For example, if you want your students to demonstrate a comprehensive knowledge of Manifest Destiny then you'll probably want them to create longer documentary-style videos by using a tool like WeVideo. On the other hand, if you just want your students to share some highlights of their field trips then a simple tool like Animoto might be adequate.
2. Your students' skill level with video editing tools. Early in the school year when my students don't have a lot of experience with video production tools, I like to start them out with relatively simple tools. Then as they year progresses I introduce them to move complex tools.
3. Be concise. Last year Wistia published some interesting data that revealed that people are more likely to watch multiple short videos all the way through than one longer video of equivalent length. Consider having your students use the YouTube annotations tool to create a series of linked, short videos about a topic rather than one long video. Directions for doing this can be found here.