The study assessed the Global Quality Score (GQS) and informational engagement of users with YouTube videos on the Brazilian public health system (SUS). The YouTube video search tool was used with the Portuguese keywords 'unified health system' and 'SUS'. The first 100 videos returned in the search were studied, using the GQS to measure their educational value, usefulness, and information quality. Users' engagement with the videos was calculated based on their number of likes/reactions and comments. Other data collected were authorship, year of publication, topic approached, target audience, video length, and use of references. Two trained and calibrated researchers collected the data. Multiple analysis was performed with Logistic Regression, using a 95% confidence interval and significance of p<0.05. There were no poor or generally poor GQS scores (scores 1 and 2) and most videos (58%) achieved moderate or good scores (scores 3 and 4). Videos published after the onset of COVID-19 had a 70% lower chance of engagement than those published in pre-pandemic years (OR: 0.30; 95%CI: 0.12-0.74). Videos that targeted healthcare professionals were 72% less likely to achieve higher GQS scores, than those with an unidentified target audience (OR: 0.28; 95%CI: 0.10-0.75). The informational engagement of the videos showed fewer comments than likes/reactions. Most YouTube videos about the SUS had moderate or good global quality, which was associated with their period of publication and choice of target audience.