diff --git a/doc/BUILD.md b/doc/BUILD.md
index e4bcb919..168fa265 100644
--- a/doc/BUILD.md
+++ b/doc/BUILD.md
@@ -445,6 +445,8 @@ Adds support for multiple codecs: ATRAC3 (`.at3`), ATRAC3plus (`.at3`), XMA1/2 (
 
 vgmstream's FFmpeg builds for Windows remove many unnecessary parts of FFmpeg to trim down its gigantic size, and are also built with the "vgmstream-" prefix to avoid clashing with other plugins. Current options can be seen in `ffmpeg_options.txt`. Linux usually links to the system's FFmpeg without issues.
 
+Note that the options above use *libopus*, but you can use FFmpeg's *Opus* by removing `--enable-libopus` and changing `--enable-decoder`'s `libopus` to `opus`. libopus is preferable since FFmpeg's Opus decoding is buggy in some files.
+
 For GCC simply use autotools (configure, make, make install), passing to `configure` the above options.
 
 For MSCV it can be done through a helper: https://github.com/jb-alvarado/media-autobuild_suite
diff --git a/doc/TXTH.md b/doc/TXTH.md
index d471a5fd..8f88d827 100644
--- a/doc/TXTH.md
+++ b/doc/TXTH.md
@@ -28,7 +28,7 @@ Also check the [examples](#examples) section for some quick recipes, of varying
 
 
 ## Issues
-The `.txth` may be rejected if incorrect commands are found. Since at the moment vgmstream can't communicate why a file is rejected, try starting with a simple case (see examples) then add more complex commands until it fully works.
+The `.txth` may be rejected if incorrect commands are found. Errors are shown in the console log (see *USAGE* guide), better try starting with a simple case (see examples) then add more complex commands until it fully works.
 
 Extension must be accepted/added to vgmstream (plugins like foobar2000 only load extensions from an accepted list in `formats.c`), or one could rename to any supported extension (like `.vgmstream`), or leave the file extensionless. Before renaming consider reporting the unknown extension so it can be added to the list (so similar games benefit, as long as the extension is a good fit). Some plugins allow playing unknown extensions too.
 
@@ -221,7 +221,7 @@ interleave_first_skip = (value)
 #### ID VALUES
 Validates that `id_value` (normally set as constant value) matches value read at `id_check`. The file will be rejected and won't play if values don't match.
 
-Can be redefined several times, it's checked whenever a new id_offset is found. `id_offset` can be used as an alt for `id_check`
+Can be redefined several times, it's checked whenever a new id_check is found. `id_offset` can be used as an alt for `id_check`
 ```
 id_value = (value)
 id_check = (value)
diff --git a/doc/USAGE.md b/doc/USAGE.md
index e8c61ee3..7e6687e9 100644
--- a/doc/USAGE.md
+++ b/doc/USAGE.md
@@ -213,15 +213,29 @@ extensions as a way to force them into vgmstream without renaming.
 #### Related issues
 Also be aware that other plugins (not vgmstream) can tell the player they handle
 some extension, then not actually play it. This makes the file unplayable as
-vgmstream doesn't even get the chance to parse that file, so you may need to
-disable the offending plugin or rename the file (for example this may happen with
-`.asf` in foobar2000/Winamp, may be fixed in newer versions).
+vgmstream doesn't even get the chance to parse it, so you may need to disable
+the offending plugin or rename the file to the fake extension shown above (for
+example this may happen with `.asf` in foobar2000/Winamp, may be fixed in newer
+versions).
 
 When extracting from a bigfile, sometimes internal files don't have a proper
 extension. Those should be renamed to its correct one when possible, as the
 extractor program may guess wrong (like `.wav` instead of `.at3` or `.wem`).
 If there is no known extension, usually the header id/magic string may be used instead.
 
+#### Windows 10 folder bugs
+Windows 10's *Web Media Extensions* is a pre-installed package seems to read metadata
+from files like `.ogg`, `.opus`, `.flac` and so on when opening a folder. However
+it tends to noticeably slow down opening folders, also seems to crash and leave files
+unusable when reading unsupported formats like Switch Opus (rather than Ogg Opus).
+
+Renaming extensions should prevent those issues, or just uninstall those *Web
+Media Extension* better experience anyway.
+
+#### Fallout SFX .ACM
+Due to technical limitations, to play Fallout 1 SFX you need to rename them from
+`.acm` to `.wavc` (forces mono).
+
 ### Demuxed videos
 vgmstream also supports audio from videos, but usually must be demuxed (extracted
 without modification) first, since vgmstream doesn't attempt to support most of them