ytdl_hook: always set HTTP headers

In some cases HTTP headers were not set, leading to some sites not
working despite being supported by yt-dlp/youtube-dl.

player/lua/ytdl_hook.lua

@@ -525,6 +525,10 @@ local function add_single_video(json)
     local max_bitrate = 0
     local requested_formats = json["requested_formats"]
     local all_formats = json["formats"]
+    local has_requested_formats = requested_formats and #requested_formats > 0
+    local http_headers = has_requested_formats
+                         and requested_formats[1].http_headers
+                         or json.http_headers
 
     if o.use_manifests and valid_manifest(json) then
         -- prefer manifest_url if present
@@ -554,7 +558,6 @@ local function add_single_video(json)
     if streamurl == ""  then
         -- possibly DASH/split tracks
         local res = nil
-        local has_requested_formats = requested_formats and #requested_formats > 0
 
         -- Not having requested_formats usually hints to HLS master playlist
         -- usage, which we don't want to split off, at least not yet.
@@ -591,7 +594,6 @@ local function add_single_video(json)
         end
         -- normal video or single track
         streamurl = edl_track or json.url
-        set_http_headers(json.http_headers)
     end
 
     if streamurl == "" then
@@ -599,6 +601,8 @@ local function add_single_video(json)
         return
     end
 
+    set_http_headers(http_headers)
+
     msg.verbose("format selection: " .. format_info)
     msg.debug("streamurl: " .. streamurl)