I've built ffmpeg... Put it to ./external...
When starting to build FOBS, I see:

UnicodeDecodeError: 'ascii' codec can't decode byte 0x81 in position 9: ordinal not in range(128):
  File "C:\develop\fobs\SInit", line 18:
    env = Environment(options = opts)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Environment.py", line 933:
    apply_tools(self, tools, toolpath)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Environment.py", line 106:
    env.Tool(tool)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Environment.py", line 1583:
    tool(self)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\__init__.py", line 175:
    apply(self.generate, ( env, ) + args, kw)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\default.py", line 41:
    SCons.Tool.Tool(t)(env)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\__init__.py", line 175:
    apply(self.generate, ( env, ) + args, kw)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\mslink.py", line 214:
    include_path, lib_path, exe_path = SCons.Tool.msvc.get_msvc_paths(env,version)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\msvc.py", line 565:
    include_path = get_msvc_path(env, "include", version)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\msvc.py", line 354:
    return _get_msvc8_path(path, str(version_num), platform, suite)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\msvc.py", line 296:
    dirs = _parse_msvc8_overrides(version, platform, suite)
  File "c:\develop\fobs\scons-local\scons-local-0.98.5\SCons\Tool\msvc.py", line 194:
    settings_path = settings_path.replace(r'%' + env_var + r'%', env_vars[env_var])
scons: Reading SConscript files ...
AttributeError: 'module' object has no attribute 'root':
  File "C:\develop\fobs\SConstruct", line 10:
    full_ffmpeg_path= os.path.abspath(ffmpeg_path.replace('#',fobs.root+"/"))