Problems when programming the ESP8266-12E using Arduino software/IDE

I followed this instructables tutorial to program the ESP8266-12E. I was able to program the board the first time correctly, however trying to make changes and update the code didn't work. When I tried to update the code using the arduino IDE, I got the following messages:

warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed

So I tried changing some settings with no luck. By trial and error I found the solution. On the board is a button called "Flash". This button needs to be held down when connecting the USB cable between the board and your computer. If not, it is not possible to program using the default arduino settings. I expect there is some way to enable this however I haven't yet dug deeper in to this problem, as I just wanted to get some basic functionality working.