Add explainations for the codec tests
Add explainations for the codec tests

chiefcll/html5test,ya7lelkom/html5test,chiefcll/html5test,ya7lelkom/html5test,chiefcll/html5test,mpopp75/html5test,ya7lelkom/html5test,mpopp75/html5test,mpopp75/html5test,NielsLeenheer/html5test,NielsLeenheer/html5test,NielsLeenheer/html5test