In this php script Video Upload Form, how can I limit the number of characters that can be entered into the description text area?

Thanks

Code:
<!--Begin Left Column-->
    <div id="column-left-2">
    <!--Begin Upload Menu-->
      <div class="header-narrow"><h3>[var.lang_main_menu]</h3></div>
      <div class="whats-showing">
        <ul>
          <li><a href="uploader.php">[var.lang_upload_video]</a></li>
              <!--[var.audio_inner_upload_video_form1;htmlconv=no;comm]-->
	      <li><a href="image_uploader.php">[var.lang_upload_image]</a><!--[onload;block=li;when [var.enable_images]=1;comm]--></li>
        </ul>
      </div>
     <div class="container-narrow-bottom"></div><!--End Upload Menu-->

   <!--Begin Left Advert-->
      <div class="container-narrow-top"></div>
        <div id="advert-left">
          <!--[var.ads_left;htmlconv=no;comm]-->
        </div>
      <div class="container-narrow-bottom"></div><!--End Left Advert-->

    </div><!--End Left Column-->

  <!--Begin Right Column-->
    <div id="column-right-2">

      <div class="header-wide"><h2>[var.lang_upload_video]</h2></div>
        <div class="container-wide">
          <!--BEGIN - Addon Video Grabber Code can be added in this div-->
          <div>

          </div>
          <!--END - Addon Video Grabber Code can be added in this div-->

          <!--Begin Upload Video Form-->
          <form name="form_upload" action="uploader.php" method="post">
            <div id="upload-video">
              <ul>
                <li style="width:240px; text-align:right;"><strong>[var.lang_title]:</strong></li>
                <li style="width:400px; text-align:left;"><input name="title" type="text" class="upload-video-form-input" value="[var.title]" size="38" />
                </li>

                <li style="width:240px; text-align:right;"><strong>[var.lang_description]:</strong></li>
                <li style="width:400px; text-align:left;"><textarea rows="4" name="description" cols="29" class="upload-video-form-input">[var.description]</textarea>
                </li>

                <li style="width:240px; text-align:right;"><strong>[var.lang_tags]:</strong></li>
                <li style="width:400px; text-align:left;"><input name="tags" type="text" class="upload-video-form-input" value="[var.tags]" size="38" />
                </li>

                <li style="width:240px; text-align:right;">&nbsp;</li>
                <li style="width:300px; text-align:left;" class="upload-video-tags">
                [var.lang_enter_tags].<br />
                      [var.lang_enter_tags_description].</li>

                <li style="width:240px; text-align:right;"><strong></strong></li>
                <li style="width:400px; text-align:left;">
                <input type="hidden" name="channel" value="SINGLECHANNEL"></li>

               
           	    <li style="width:240px; text-align:right;"><strong></strong></li>
				<li style="width:400px; text-align:left;">
                <input type="hidden" name="public_private" value="public"></li>

           	    <li style="width:240px; text-align:right">&nbsp;</li>
           	    <li style="width:400px; text-align:left;">
           	      <input class="button-form" type="submit" value="Next &gt;&gt;" name="B3" />
           	    </li>
           	  </ul>
            </div>
            <input class="upload-video-form-input" type="hidden" name="form_submitted" value="yes" />
          </form>
          <div class="clear-fix"></div>
        </div>
      <div class="container-wide-footer"></div>

    </div><!--End Right Column-->