Effective curricular support systems must include resources supporting high-fidelity activity implementation. We examined the frequency of pre-kindergarten teachers' online demonstration video viewing and its association with fidelity of implementation of a math and science curriculum. We found a range in frequency of video viewing and a positive relationship between video viewing and fidelity of implementation. We interviewed a subsample of selected teachers to understand their use and perceptions of videos. Themes suggesting teachers purposefully selected videos and perceived specific video characteristics as useful for activity implementation could inform future creation of implementation supports and support for teachers' use of resources.