diff --git a/scripts/fetch-ffmpeg.mjs b/scripts/fetch-ffmpeg.mjs
index 07c78e5f1..222485d97 100644
--- a/scripts/fetch-ffmpeg.mjs
+++ b/scripts/fetch-ffmpeg.mjs
@@ -156,8 +156,23 @@ const GPL_LIBS = [
 /** Worse than GPL: these make the binary unredistributable at all. */
 const NONFREE_LIBS = ["libfdk-aac", "libfdk_aac"];
 
-/** The encoders the export path actually selects, per platform. */
-const WANTED_ENCODERS = {
+/**
+ * The hardware encoders we look for in a vendored build, per platform.
+ *
+ * REPORTED, NOT VERIFIED — and the distinction has bitten. Presence in
+ * `-encoders` means the build was compiled with the wrapper; it says nothing
+ * about whether the encoder RUNS on a given machine. The vendored builds list
+ * `h264_vaapi` on Linux, yet on any host with libva < 2.21 (Ubuntu 24.04 LTS
+ * included) it used to take the whole process down with SIGABRT rather than
+ * return an error, because the implib trampoline `abort()`s on a symbol it
+ * cannot resolve. See issues #552 and #576.
+ *
+ * So this list drives a log line and nothing else. The only evidence that an
+ * encoder works is a frame going through it — `vaapi_encodes_from_an_exported_dmabuf`
+ * in `crates/compositor/src/pipeline_linux.rs` is that evidence for the Linux
+ * hardware path, and the export falls back to software whenever it is absent.
+ */
+const REPORTED_ENCODERS = {
 	win32: ["h264_nvenc", "h264_qsv", "h264_amf"],
 	linux: ["h264_nvenc", "h264_vaapi"],
 };
@@ -230,13 +245,14 @@ function assertLgpl(exePath, extraEnv) {
 
 function reportEncoders(exePath, platform) {
 	const encoders = run(exePath, ["-hide_banner", "-encoders"]).stdout ?? "";
-	const wanted = WANTED_ENCODERS[platform] ?? [];
+	const wanted = REPORTED_ENCODERS[platform] ?? [];
 	const found = wanted.filter((e) => new RegExp(`\\s${e}\\s`).test(encoders));
 	const missing = wanted.filter((e) => !found.includes(e));
-	console.log(`  hardware encoders: ${found.join(", ") || "(none)"}`);
+	console.log(`  hardware encoders present (not verified): ${found.join(", ") || "(none)"}`);
 	if (missing.length > 0) {
-		// Not fatal: which encoders a build exposes is separate from which GPU the
-		// machine has. selectVideoEncoder() probes at runtime regardless.
+		// Not fatal, and deliberately so: which encoders a build EXPOSES is
+		// separate both from which GPU the machine has and from whether the
+		// encoder is usable there at all. The runtime probes regardless.
 		console.log(`  not in this build: ${missing.join(", ")}`);
 	}
 }