Dovetail works great as a user generated research repository, however the insights you gain from the system are still highly dependent on individual contributors.
The problem with this is that different people may perceive the same set of insights differently leading to different interpretations and tagging systems that may not be standardized across teams.
With Speak, you can set up custom categories in addition to the default insights that are pulled automatically for you as more media is added to your account.
For instance, instead of manually tagging every time someone mentions a specific brand, problem, name or topic, you can train Speak to extract that information for you across every single file in your repository.