Go into your cpanel area go into templates/index.tpl find this line:

{section name=i loop=$new_video start=0 max=4}

<td></td>
<td width="25%" align="center">
<A href="{$baseurl}/view/{$new_video[i].VID}/{$new_video[i].title|lower|regex_replace:"/[^a-z0-9]+/":"-"}/">[img]{$tmburl}/1_{$new_video[i].VID}.jpg[/img]
{$new_video[i].title}</a>

</td>
{/section}

</tr>
</table>



Replace It All with:

{section name=i loop=$new_video start=0 max=4}

<td></td>
<td width="25%" align="center">
<A href="{$baseurl}/view/{$new_video[i].VID}/{$new_video[i].title|lower|regex_replace:"/[^a-z0-9]+/":"-"}/">[img]{$tmburl}/1_{$new_video[i].VID}.jpg[/img]
{$new_video[i].title}</a>

</td>
{/section}

</tr>

<tr>

{section name=i loop=$new_video start=4 max=4}

<td></td>
<td width="25%" align="center">
<A href="{$baseurl}/view/{$new_video[i].VID}/{$new_video[i].title|lower|regex_replace:"/[^a-z0-9]+/":"-"}/">[img]{$tmburl}/1_{$new_video[i].VID}.jpg[/img]
{$new_video[i].title}</a>

</td>
{/section}

</tr>
</table>

That will give you 8, you can repeat and change as necessary to do more.