Help me secure my video content

I'm a teacher, planning to launch an online course. As it is a video course, the security of the video files is a concern. I need technical assistance in hosting the videos in a secure and cheap way (looked into services like VDOcipher but they are too expensive for my budget). What I need from you: 1. Videos should not be downloadable through video grabbers such as IDM. (I know any video can still be captured through screen recording. ) 2. Videos should be playable across different platforms/browsers. 3. I don't mind what kind of protection it is (RTMP/DRM, I did some research) as long as it keeps my videos safe. 4. Videos should be playable at at least 3 resolutions - 1080P, 720P, 360P. I don't mind if there is an option for slow internet users for a secure offline download as long as the file is secure. I'm planning on using Amazon s3 for hosting the files, but if you have better idea, I'm open to it. I have just done basic research on my part, and I don't have any technical knowledge at all.