If you want use the default value you need to download the publish profile in your dashboard for your site:
[UPDATE for the new Azure UI]
It will be an XML file. Open it and find your credentials. Sample:
<publishProfile
profileName="nameofyoursite - FTP"
publishMethod="FTP"
publishUrl="ftp://waws-prod-blu-001.ftp.azurewebsites.windows.net/site/wwwroot"
ftpPassiveMode="True"
userName="nameofyoursite\$nameofyoursite"
userPWD="sOmeCrYPTicL00kIngStr1nG"
destinationAppUrl="http://nameofyoursite.azurewebsites.net"
SQLServerDBConnectionString=""
mySQLDBConnectionString=""
hostingProviderForumLink=""
controlPanelLink="http://windows.azure.com">
<databases/>
</publishProfile>
Where your credentials:
publishUrl="ftp://waws-prod-blu-001.ftp.azurewebsites.windows.net/site/wwwroot"
userName="nameofyoursite$nameofyoursite"
userPWD="sOmeCrYPTicL00kIngStr1nG"
Source: Azure Web Sites FTP credentials
Connection from command line on OS X:
Console client:
ftp ftp://nameofyoursite:sOmeCrYPTicL00kIngStr1nG@waws-prod-blu-001.ftp.azurewebsites.windows.net/
Mount from the console:
mkdir /Users/<YOUR_USER>/FTP_AZURE
mount_ftp nameofyoursite:sOmeCrYPTicL00kIngStr1nG@waws-prod-blu-001.ftp.azurewebsites.windows.net/ /Users/<YOUR_USER>/FTP_AZURE
cd /Users/<YOUR_USER>/FTP_AZURE
Open for editing in Vim:
vim ftp://nameofyoursite@waws-prod-blu-001.ftp.azurewebsites.windows.ne//site/wwwroot/
Note the user name here: nameofyoursite, not nameofyoursite$nameofyoursite