One of our users was interested in using ACASI (audio computer-assisted data entry) for a survey. This is easy to do in ODK.
This link will allow you to download an example survey which uses both audio and video assistance.
The survey contains two questions, the first has audio assistance and a pictoral interface for data entry, allowing those who can’t read to choose an answer by touching a photograph.
The second question uses video with sign language.
Uploading the media files is done when you submit the XML form to the server and end user Android devices will automatically pull the required media files when you add the form to the device.