Keeping audio synchronized with video is crucial for people who are hearing impaired or rely on captions and subtitles to understand the content. The impacts on both business and the people can be many. Here are a few to keep in mind.
Comprehension 
Comprehension is difficult if they are not synchronised. People with hearing impairments heavily rely on visual cues, such as lip movements, facial expressions, and body language, to understand spoken language. If the audio is out of sync with the video, these visual cues may not match the audio, leading to confusion and difficulty in comprehending the content.
Accuracy
The accuracy of captions and subtitles is important to ensure comprehension. Captions and subtitles are essential for conveying spoken content to individuals who are deaf or hard of hearing. Accurate synchronization ensures that the text appears at the right time and corresponds correctly to the spoken words, facilitating a coherent understanding of the dialogue and narrative.
Emotion
Audio and visual elements often work together to create emotional impact and convey the mood of a scene. When the audio is out of sync, the emotional cues provided by music, sound effects, and dialogue may be lost or distorted, reducing the overall impact of the content for those who rely on visual and text cues.
User Experience
The stats are, anecdotally, that up to 80% of people have the captions turned on when they watch some streaming channels such as Netflix. A well-synchronized experience enhances user satisfaction. People who rely on captions and subtitles often appreciate shows where the content is synchronised correctly as it enhances the experience.
Education
In educational and informational videos, accuracy and synchronization are even more critical. People who rely on captions and subtitles for learning need to have clear and well-timed text to understand and absorb the information effectively.
Equality
People with hearing impairments deserve the same opportunities to enjoy and engage with content as those without impairments. Proper synchronization helps bridge the gap and ensures that everyone can have an equal and enjoyable experience.
Conclusion
Each of these reasons can be summarised by saying that having the audio and visual components of the video correctly synchronised gives a better user experience and comprehension to the viewer. That is, the message is received by the viewer correctly.