The present disclose relates to a computing cloud serving as a collaboration platform where internet connected electronic devices such as smart phones and tablets can log in to author, to review, to edit, to download and to play back digital content. By using different applications, the user may optionally play the role of an author, a reviewer or a consumer to digital content. User-authored digital content as well as recorded music are all stored in the cloud. Professional editing is possible by making overlay audio tracks and sound effect changes available on the client device and earmarking the timing relations among media clips in each media clip's associated metadata. An edited professional playlist is reusable by replacing some sound tracks in iterative host vs client actions. Personalized media insert is integrated into the normal streaming media as part of the inter-user media services or subscription services.