Can’t believe they (Microsoft) did this.
Also can’t believe there’s almost no information regarding this issue available online.
When using the Windows search on newer Windows versions (Vista, 7, 8) a filter gets applied for certain file types, resulting in HTML and PHP files not being searched entirely.
Only the „real“ content gets extracted, but it doesn’t search within the tags and attributes. Just wow! If Apple products just weren’t that useless in terms of productivity…
Rather than dabbling with the registry I suggest to use PreviewConfig or SearchFilterView for changing the indexing filter from „HTML Filter“ or „File Properties Filter“ to „Plain Text Filter“ for file types such as .html, .php etc.