In an increasingly online world, multimedia content for instructional use in chemistry is abundant. It can be difficult to discern a good resource from a poor one, even if the chemistry content in the video is accurate (which it may not be). Sound chemistry content alone does not guarantee that the videos were made with best principles in mind according to evidence-based research. Multiple authors have proposed guidelines for multimedia use and learning which are supported by research in cognitive and educational psychology. Herein we used Mayer's Multimedia Principles (MMP) to evaluate instructional chemistry videos across three topics (Chemical Bonding, Acids and Bases, and Intermolecular Forces) from multiple YouTube content creators (51 in total). We found that most videos included extraneous images and sounds which may be distracting to the viewer, in direct violation of Mayer's "Coherence" principle. For the three chemistry topics under study, no statistical differences were found in their adherence to MMP. However, there were significant differences regarding the use of extraneous images and sounds when disaggregated by content creator. This work has implications for both teachers and learners of chemistry in selecting multimedia that is cognitively supportive to learning.