If it was legal to show slide images in class, it is likely legal to show them to students via live video conferencing or in recorded videos.
This may be a surprise if you have heard that there is a big difference between class lecture slides and online conference slides - but the issue is usually less offline versus online, than a restricted versus an unrestricted audience:
The "Classroom Use Exception" does not apply to streaming media. You may need to have students independently access the content outside of your lecture videos.
If you can limit audio and video use for your course to relatively brief clips, you may be able to include those in lecture recordings or live-casts under the copyright provision called fair use. For media use longer than brief clips, you may need to have students independently access the content outside of your lecture videos. Some further options are outlined below.
There may be some practical differences in outcomes depending on where you post new course videos - for example, on eCampus.
Course Reserves provide online access to the Libraries material -- linking to Libraries subscription resources, finding ebooks where available, and much more.
Linking to publicly available online content like news websites, existing online videos, etc. is rarely a copyright issue. (Better not to link to existing content that looks obviously infringing itself - Joe Schmoe's YouTube video of the entire "Black Panther" movie is probably not a good thing to link to. But Sara Someone's 2-minute video of herself and her best friend talking over a few of the pivotal scenes may be fair use, and is not something you should worry about linking to.)
Making copies of new materials for students (by downloading and uploading files, or by scanning from physical documents) can present some copyright issues, but they're not different from those involved in deciding whether to share something online with your students when you are meeting in-person.
Where an instructor doesn't feel comfortable relying on fair use, a subject specialist librarian may be able to suggest alternative content that is already online through library subscriptions, or publicly online content.
This web site presents information about copyright law. The University Libraries make every effort to assure the accuracy of this information but do not offer it as counsel or legal advice.
Adapted from “Rapidly shifting your course from in-person to online” by Nancy Sims, University of Minnesota Libraries, and licensed under a Creative Commons Attribution-NonCommercial License.