In order to store Flex recordings in a location controlled by the customer, customers can use Twilio Functions and Amazon S3 to create a custom solution. This involves enabling WFO, creating a plugin that calls a Twilio Function when recording is complete, and setting up a Proxy Service to play back the recordings. The Proxy Server acts as a middleman, retrieving and decrypting the recording, and returning an audio stream over the HTTP protocol as a response. While this solution works for proof of concept purposes, it may need further extension to be suitable for production environments, such as adding Access Control and handling deletion of original recordings.