MPEG-4 compatible tools and players don't support MPEG-4 (F4V) files recorded with Adobe Flash Media Server 3.5.
Use the F4V Post Processor tool to prepare F4V files for video players that support H.264 and AAC formats, including Adobe Media Player. (Also use the F4V Post Processor to prepare files for editing in Adobe Premiere Pro or delivery over HTTP.) The F4V Post Processor tool aggregates the information from all the moof atoms into a single moov atom and outputs a new file. You can download the file from Adobe Flash Media Server productivity tools and sample downloads.
Adobe Flash Media Server 3.5 and later can record content in MPEG-4 (F4V) format using an industry-standard recording technology known as "fragments" or "moof atoms." (Adobe Flash Media Live Encoder 3 can also record using that technology.) Some MPEG-4 compatible tools and players do not support moof atoms, and therefore cannot recognize files recorded by Flash Media Server.
The F4V files created by the F4V Post Processor tool are compliant with the following standard: ISO/IEC 14496-12: http://standards.iso.org/ittf/PubliclyAvailableStandards/c068960_ISO_IEC_14496-12_2015.zip.