Add ability to decrypt signature for vflxuxnEY/en_US/base.js

src/helpers.cr

@@ -163,3 +163,13 @@ def search(query, client)
     end
   end
 end
+
+def decrypt_signature(a)
+  a = a.split("");
+  a.delete_at(0..2)
+  a = a.reverse
+  c = a[0]
+  a[0] = a[49 % a.size]
+  a[49] = c
+  return a.join("")
+end

src/invidious.cr

@@ -126,7 +126,14 @@ get "/watch" do |env|
     fmt_stream << HTTP::Params.parse(string)
   end
 
-  fmt_stream.reverse! # We want lowest quality first
+  if fmt_stream[0]["s"]?
+    fmt_stream.each do |fmt|
+      fmt["url"] = "#{fmt["url"]}&signature=#{decrypt_signature(fmt["s"])}"
+    end
+  end
+
+  # We want lowest quality first
+  fmt_stream.reverse!
 
   adaptive_fmts = [] of HTTP::Params
   if video.info.has_key?("adaptive_fmts")
@@ -135,6 +142,12 @@ get "/watch" do |env|
     end
   end
 
+  if adaptive_fmts[0]["s"]?
+    adaptive_fmts.each do |fmt|
+      fmt["url"] = "#{fmt["url"]}&signature=#{decrypt_signature(fmt["s"])}"
+    end
+  end
+
   rvs = [] of Hash(String, String)
   if video.info.has_key?("rvs")
     video.info["rvs"].split(",").each do |rv|