While we're constantly working to improve transcription accuracy on our side, there are a couple of ways to increase the accuracy of automatic (machine) transcription with current technology, especially if you have control over the source recording.
If your audio/video has words that are frequently used or has proper names that are uncommon, you can add these words/phrases to the custom dictionary when creating a new Automatic Transcription. You'll find this option on the New Transcription page under the Options section. This will help improve the accuracy of these specific words (but not as much as having a high quality recording).