Update app.py

app.py

@@ -6,13 +6,13 @@ class YouTubeDownloader:
     def run():
         st.header("YouTube Video Downloader")
         url = st.text_input("Enter YouTube URL to download:")
-        go_button = st.button("Go")
+        start_button = st.button("Start Download")
 
-        if go_button:
-            YouTubeDownloader.validate_url(url)
-            with st.expander("preview video"):
-                st.video(url)
-            if st.button("Download"):
+        if start_button:
+            if url:
+                YouTubeDownloader.validate_url(url)
+                with st.expander("preview video"):
+                    st.video(url)
                 YouTubeDownloader.cleanup()
                 file_ = YouTubeDownloader.download_video(url)
                 st.video(file_)
@@ -52,7 +52,7 @@ class YouTubeDownloader:
     @classmethod
     def helper_message(cls):
         st.write(
-            "> To save the video to local computer, "
+            "> To save the video to the local computer, "
             "click the vertical ... icon (aka hamburger button) in the bottom-right corner (in the video above) and click download."
         )