Ok, then how about this. I've never used WPE, so I'm not 100% sure exactly how they display packet information, but regardless of that, you need to read up on TCP/IP:
Transmission Control Protocol - Wikipedia, the free encyclopedia. The data which is sent and received in these packets is ultimately up to the discretion of the server/client. You're wondering why you don't see English within these packets? It would be redundant to send something like 'walk left' every time you wanted to walk left. It would be much easier to send something like an integer value (or even set certain packet flags), which the client can interpret as walking left. That's just a data redundancy issue. If a game sends packets frequently, then the longer the packets, obviously the less efficient it's going to be (which is why they'll mostly try to shorten it as much as possible, and let the client deal with it instead).
While stumbling around in WPE (or something like Wireshark) may allow you to empirically discover the nature and formatting of the packets, if you truly want to find out how they're structured, you're better off decompiling the .swf file and taking a look at the corresponding .as files.