Add URL validation and ytdlp error messages to translations

Added new translation keys for URL validation and ytdlp error messages in all supported languages. This improves error reporting and user feedback for invalid URLs and common download issues.

src/gui/ytsage_gui_main.py

@@ -29,7 +29,7 @@ from PySide6.QtWidgets import (
 )
 
 from src.core.ytsage_downloader import DownloadThread, SignalManager  # Import downloader related classes
-from src.core.ytsage_utils import check_ffmpeg, load_saved_path, parse_yt_dlp_error, save_path, should_check_for_auto_update
+from src.core.ytsage_utils import check_ffmpeg, load_saved_path, parse_yt_dlp_error, save_path, should_check_for_auto_update, validate_video_url
 from src.core.ytsage_yt_dlp import get_yt_dlp_path, setup_ytdlp  # Import the new yt-dlp functions
 from src.gui.ytsage_gui_dialogs import (  # use of src\gui\ytsage_gui_dialogs\__init__.py
     AboutDialog,
@@ -707,6 +707,12 @@ class YTSageApp(QMainWindow, FormatTableMixin, VideoInfoMixin):  # Inherit from
         if not url:
             self.signals.update_status.emit(_("main_ui.invalid_url_or_enter"))
             return
+        
+        # Validate URL before processing
+        is_valid, error_message = validate_video_url(url)
+        if not is_valid:
+            self.signals.update_status.emit(error_message)
+            return
 
         self.signals.update_status.emit(_("main_ui.analyzing_preparing"))
         threading.Thread(target=self._analyze_url_thread, args=(url,), daemon=True).start()
@@ -788,6 +794,12 @@ class YTSageApp(QMainWindow, FormatTableMixin, VideoInfoMixin):  # Inherit from
                 self.status_label.setText(_('download.please_enter_url_and_path'))
             return
         # --- End Path Change ---
+        
+        # Validate URL before starting download
+        is_valid, error_message = validate_video_url(url)
+        if not is_valid:
+            self.status_label.setText(error_message)
+            return
 
         # Get selected format
         format_id = self.get_selected_format()