Counseling is considered a first-line conservative therapy with respect to temporomandibular joint disorders (TMJD). Nowadays, 50 to 80% of patients acquire health information from the internet before turning to professionals. The purpose of this study has been to investigate the quality of information about TMJD that patients can obtain from YouTube. A YouTube.com search was conducted using the terms "temporomandibular joint disorder"; "limited movement of the mandible"; and "mandibular joint pain". The videos identified were assessed independently by two panels of three professional and lay reviewers with HONcode, modified DISCERN (MD) and the global quality scale (GQS). A total of 106 videos were included. The professional reviewers reported a mean HONcode score of 4.148 ± 1.314 and a mean MD score of 2.519 ± 1.267, testifying to a modest general quality of the videos. The mean GQS score was 2.987 ± 1.012 for the professional and 3.469 ± 0.891 for the lay reviewers (p < 0.001). The correlations between the ratings were significant between the reviewers within the same group but not between the two groups. The presence of animations significantly influenced the GQS score expressed by the lay reviewers (p = 0.011) but not that of the professionals (p = 0.640). The quality of the information on TMJD on YouTube is generally of poor quality. Healthcare systems and professionals should be prepared to correct misinformation and build trusting relationships with patients which are based on quality counseling. Similarly, academic institutions should produce quality content that leads patients with TMJD toward a correct diagnostic-therapeutic process.